Si (巳, sì) is the sixth of the Twelve Earthly Branches. It is the branch paired with the Snake in the Chinese zodiac, commonly mapped to the 9:00–11:00 a.m. double-hour, the solar-term month from Lixia (立夏) to just before Mangzhong (芒种), and a south-southeast direction. In later correspondence systems, Si is associated with Fire and usually classified as a yin branch.
Those statements belong to different historical layers. The branch itself is an ancient ordering sign; the 9–11 a.m. range is a modern clock conversion; the Snake is a zodiac correspondence; Fire, hidden stems, combinations, and clashes belong to cosmological or divinatory frameworks that developed around the branch system. Keeping these layers separate is the clearest way to understand the Si Earthly Branch meaning.
Direct Answer: What Does Si (巳) Mean?
| Question | Concise answer | Type of information |
|---|---|---|
| What is Si? | The sixth Earthly Branch, after Chen (辰) and before Wu (午) | Ordered calendar sign |
| How is 巳 pronounced? | Sì, fourth tone | Modern Mandarin |
| Which animal corresponds to Si? | Snake (蛇, shé) | Chinese zodiac correspondence |
| What is the Si hour? | Commonly converted as 09:00–11:00 | Modern mapping of a traditional double-hour |
| What is the Si month? | In solar-term month systems, Lixia to just before Mangzhong | Calendrical convention |
| What direction is Si? | South-southeast, centered near 150° | Branch/compass correspondence |
| What is the Si five element? | Fire; Si is commonly classed as yin | Traditional cosmological correspondence |
| What are the Si hidden stems? | Bing (丙), Wu (戊), and Geng (庚) in a common Bazi rule | Later divinatory framework |
How to Pronounce 巳 and Distinguish It from 已 and 己
The modern Standard Mandarin pronunciation of 巳 is sì, with the falling fourth tone—the same syllable and tone as 四, “four.” An English approximation such as “suh” can only be a rough prompt: begin with an unaspirated s sound and let the pitch fall sharply. Pinyin sì describes the modern reading; it is not a claim about how the character sounded in every ancient period.
| Character | Pinyin | Core modern use | Visual cue in common typefaces |
|---|---|---|---|
| 巳 | sì | Sixth Earthly Branch | The inner stroke curls upward but does not project beyond the top |
| 已 | yǐ | Already; to stop or finish in older uses | The inner stroke is lower or only partly raised |
| 己 | jǐ | Self; the sixth Heavenly Stem | The top horizontal is commonly open on the left |
This distinction matters in phrases such as Yisi (乙巳): Yi (乙) is the Heavenly Stem and Si (巳) is the Earthly Branch. Replacing 巳 with 已 or 己 changes the term.
Si as the Sixth Earthly Branch
The Twelve Earthly Branches run in this order: Zi (子), Chou (丑), Yin (寅), Mao (卯), Chen (辰), Si (巳), Wu (午), Wei (未), Shen (申), You (酉), Xu (戌), and Hai (亥). Si is therefore number 6 in a repeating 12-part sequence.
Branches have been used to organize days, months, years, time periods, and directions. They also pair with the Ten Heavenly Stems to form the 60-unit ganzhi (干支) or sexagenary cycle. The animal cycle is one familiar layer of this larger system: Si corresponds to the Snake, but the written branch is not merely an abbreviation for the animal.
For a complete animal-and-branch overview, see Eastern Story’s guide to the 12 Chinese zodiac signs. The present page stays with the sixth branch itself.
The Earliest Written Forms and the Etymology of 巳
What the early script record shows
The Chinese University of Hong Kong’s character database records examples of 巳 in oracle-bone, bronze-inscription, and small-seal forms. That evidence establishes a long written history and visible variation across media. It does not, by itself, make every curved form a literal picture of one object.
Popular explanations often say that the early graph depicts either a snake or a fetus. These are interpretations, not a single uncontested conclusion. The safest account is that early forms are attested, the graph became the conventional sixth branch, and later dictionaries supplied their own explanations of its form and seasonal meaning.
What the Shuowen Jiezi says
The Eastern Han dictionary Shuowen Jiezi (《说文解字》) explains the graph through the fourth month and says, in part, “四月阳气巳出，阴气巳藏，万物见，成文章”—yang qi has emerged, yin qi is concealed, and the myriad things become visible and patterned. The received entry then connects 巳 with a snake and calls it pictographic.
This is valuable evidence for how an early imperial lexicographer understood the character. It should be presented as Xu Shen’s ancient explanation, not as the final verdict of modern paleography. The similar sounds and meanings later associated with words such as si (嗣, succession) or si (祀, sacrifice) also do not prove that all of them derive from one simple picture-story.
Si Hour: Why It Is Commonly Mapped to 9–11 a.m.
A traditional day can be divided into 12 branch-labeled periods. In the modern conversion table, each period occupies two clock hours, placing Si hour (巳时) at 09:00–11:00. Its midpoint is 10:00 a.m., after Chen hour (07:00–09:00) and before Wu hour (11:00–13:00).
The old day-part name yuzhong (禺中), also written 隅中, means the time approaching noon and is commonly aligned with Si hour in later reference tables. Historical timekeeping was not simply a digital clock with old labels: systems changed, daylight observation mattered, and local apparent solar time was not the same as a modern national standard time zone. For most readers, 9–11 a.m. is the useful conventional conversion rather than an invariant historical timestamp.
A familiar folk story says the Snake was assigned to Si because snakes emerged from their holes during this part of the morning. It works as a mnemonic, but it is not established as the documented historical origin of the zodiac pairing. Claims that Si hour is automatically a peak-performance period, a universal auspicious time, or a medically privileged two-hour window belong to separate traditional or modern advice systems, not to the calendar definition.
Si Month: Solar Terms, Lunar Month, and Gregorian Dates
Si month (巳月) can be misunderstood because three calendars are often compressed into one sentence. A solar-term month, the fourth lunar month, and a range of Gregorian dates are related but not identical.
1. The solar-term or “branch month”
In common ganzhi-month and Bazi conventions, Si month begins at the exact arrival of Lixia (立夏, “Summer Commences”) and ends when Mangzhong (芒种, “Corn on Ear”) arrives. It therefore includes the full interval from Lixia through Xiaoman (小满) and stops immediately before Mangzhong—not at Xiaoman.
On the Gregorian calendar, this usually falls roughly from May 5 or 6 to June 5 or 6. These are guide dates, not permanent boundaries. The astronomical instant changes by year, and the displayed civil time depends on time zone. For a person or event close to a boundary, the year, location, and chosen calendrical convention all matter.
2. The fourth lunar month
The traditional Chinese calendar is lunisolar. Its numbered months begin with the new moon, while solar terms help keep the calendar aligned with the seasons. The fourth lunar month can overlap much of the Si seasonal period, which explains the conventional association, but its first day is not defined by Lixia.
The year 2025 makes the distinction visible. The Hong Kong Observatory’s conversion table places the first day of the fourth lunar month on April 28, while Lixia falls on May 5 and Mangzhong on June 5. Thus “lunar fourth month,” “Si solar month,” and “May 5–June 5” answer different questions.
3. “Snake month” in popular language
Because Si corresponds to the Snake, some popular calendars call Si month a “Snake month.” This is a convenient cultural label rather than the single official name used by every historical calendar tradition.
Si Direction in the Twelve-Branch and Twenty-Four Mountains Systems
In directional mapping, Si points south-southeast, or southeast leaning toward south. Using the modern compass convention of north as 0° and measuring clockwise, its center is about 150°.
The common Twenty-Four Mountains (二十四山) compass divides 360° into 24 sectors of 15° each. On that modern luopan-style division, the Si mountain occupies 142.5°–157.5°. It sits beside, but is not identical to, the Xun mountain (巽, 127.5°–142.5°) and the Bing mountain (丙, 157.5°–172.5°).
| Directional label | Common center | Common 24-mountain span |
|---|---|---|
| Xun (巽) | 135° | 127.5°–142.5° |
| Si (巳) | 150° | 142.5°–157.5° |
| Bing (丙) | 165° | 157.5°–172.5° |
Calling the whole southeast “Si” erases useful distinctions. In the Eight Trigrams layout, the broader southeast palace is Xun; in the Twenty-Four Mountains, Xun and Si are two neighboring 15° mountains within that broader region. Traditional feng shui schools use these labels in technical ways, but the directional correspondence itself is not a prescription for arranging a home, choosing a city, or improving fortune.
Si and the Snake in the Chinese Zodiac
Si corresponds to the Snake (蛇, shé) in the 12-animal cycle. The order is Dragon–Snake–Horse because the corresponding branches are Chen–Si–Wu. The branch supplies the formal position; the animal supplies the memorable zodiac image.
The pairing supports year names, zodiac art, festival design, and everyday speech such as “a Snake year.” It does not mean that every use of 巳 is literally about a biological snake. A Si hour, Si month, Si direction, and Yisi year all use the same branch position in different contexts.
Snake symbolism also changes with context. Shedding can suggest renewal in modern design; coiling can convey continuity; a snake in a myth may be protective, dangerous, ancestral, erotic, medicinal, or transformative. No single list—“wise, secretive, strategic, mysterious”—captures the full cultural history. Eastern Story’s Snake zodiac guide explores the animal layer in more detail.
Si in the Sexagenary Cycle and Yisi Years
The Ten Heavenly Stems and Twelve Earthly Branches combine in a 60-step cycle. Si pairs with five yin stems: Yi (乙), Ding (丁), Ji (己), Xin (辛), and Gui (癸). The five Si-year names are therefore Yisi (乙巳), Dingsi (丁巳), Jisi (己巳), Xinsi (辛巳), and Guisi (癸巳).
2025 is an Yisi (乙巳) year of the Snake in the official Gregorian–lunar conversion table published by the Hong Kong Observatory. Earlier Yisi years include 1905 and 1965; the same stem-branch pair returns every 60 years. In ordinary zodiac usage, the lunar new year marks the change of animal year, while some astrological schools use Lichun as a technical boundary. A date near the transition should always be read according to the stated convention.
A person’s zodiac birth-sign year returns every 12 years, while the identical stem-branch name returns every 60. Those are related cycles, not the same interval. The Benmingnian guide explains the 12-year birth-sign return as a separate folk custom.
Fire and Yin-Yang Correspondences
In a widely used correspondence table, Si belongs to Fire and is classified as a yin branch. Its neighboring branch Wu (午) is also Fire and is commonly classified as yang. This places Si and Wu together in the summer sector while preserving two positions within it.
Five Elements here means wuxing (五行), a traditional system of correlated phases or processes. “Si is Fire” is therefore a classification within historical cosmology, not a statement that the written character contains physical flame or measurable human energy.
Si should not be called “Furnace Fire” or “Great Post-Station Fire.” Names such as Furnace Fire (炉中火) belong to the separate nayin (纳音) classification of particular stem-branch pairs, not to the standalone branch 巳. “Great Post-Station Earth” (大驿土) is another nayin name; “Great Post-Station Fire” is a common online mix-up.
Hidden Stems: A Later Bazi Framework
In a common Bazi (八字) rule, Si “stores” three Heavenly Stems: Bing Fire (丙), Wu Earth (戊), and Geng Metal (庚). The usual shorthand is 巳藏丙戊庚.
“Hidden” is a technical metaphor within later fate-calculation traditions. It does not describe components visible inside the graph 巳 or substances physically contained in a place, hour, or person. Schools may rank the three stems with terms such as primary, middle, or residual qi, but percentage formulas such as 60/30/10 are not a universal historical standard and are best omitted from a general reference page.
Combinations, Clashes, Punishments, and Harms as Traditional Models
Later cosmological and divinatory manuals relate branches through patterned sets. These relationships are useful for reading the vocabulary of Bazi and related traditions, but the labels are structural rules—not ready-made predictions about health, money, marriage, or career.
| Traditional relationship | Branches involving Si | What the label means at the reference level |
|---|---|---|
| Three Harmony (三合) | Si–You–Chou (巳酉丑) | A three-branch set commonly associated with Metal |
| Three Meetings (三会) | Si–Wu–Wei (巳午未) | The contiguous summer/fire-direction set |
| Six Harmony (六合) | Si–Shen (巳申) | A conventional paired relation |
| Six Clash (六冲) | Si–Hai (巳亥) | An opposing branch pair; their directions are approximately opposite |
| Three Punishments (三刑) | Yin–Si–Shen (寅巳申) | A later patterned set whose internal direction is explained differently by schools |
| Six Harms (六害) | Yin–Si (寅巳) | A conventional pair in another relationship table |
The Si–Shen pair demonstrates why a simple personality template fails: it appears as a harmony pair in one table and within a punishment set in another. Practitioners resolve such overlaps through broader chart rules and school-specific priorities. The phrase Si–Hai clash (巳亥冲) identifies an opposition in the model; by itself it does not announce separation, illness, travel, or sudden misfortune.
Si is also not automatically an “Traveling Horse” or Yima (驿马) star. In one common rule, the reference group Hai–Mao–Wei assigns Yima to Si; other reference groups assign it to different branches. The label depends on what the calculation starts from, often a year or day branch.
What One Si Cannot Tell You About Personality, Health, or Fate
In Four Pillars or Bazi, the same branch can appear in the year, month, day, or hour position, alongside four stems and three other branches. Traditional interpretation also considers season, relationships across the whole chart, timing cycles, and the rules of a particular lineage. One Si cannot support a fixed conclusion about temperament, a spouse, children, career, residence, wealth, or health.
Statements such as “Si people are outwardly warm but inwardly cold,” “a Si day means an overseas spouse,” or “a Si hour predicts talented children” are modern stereotypes presented with more certainty than the underlying system allows. The same applies to assigning heart, eye, digestive, sleep, or emotional conditions from the Fire correspondence. A cultural reference page can explain the vocabulary without turning a branch sign into a diagnosis or personal forecast.
Snake Imagery, Fuxi and Nüwa, and Changing Cultural Meanings
Early snake motifs and later art
Snake-shaped and snake-like motifs have a history far older than a modern zodiac personality list. The Palace Museum traces snake imagery in objects from Neolithic painted pottery through Shang and Zhou bronzes and later textiles. Across those periods, the form could be ornamental, protective, numinous, threatening, or auspicious depending on the object and setting.
Fuxi and Nüwa
Museum collections preserve images of the culture heroes Fuxi (伏羲) and Nüwa (女娲) with human upper bodies and intertwined serpent-like lower bodies. In tomb and cosmological art, they may hold the compass and square and appear within an ordered image of the universe. These works show that serpentine form could carry ancestral and cosmic meaning; they do not reduce every snake image to one symbol such as fertility or rebirth.
Snake, dragon, and the folk name “little dragon”
Serpentine bodies are important in the visual history of the Eastern dragon (龙), and some Chinese communities call the Snake a “little dragon” (xiaolong, 小龙). This is a folk name, not a universal ancient biological classification. For the dragon as a distinct cultural figure, read the Eastern dragon meaning guide.
“巳巳如意” and Other Modern Wordplay
巳巳如意 is pronounced like 事事如意, a wish that “everything goes as one hopes.” It became especially visible around the 2025 Yisi Snake year in festival themes, public greetings, and cultural merchandise. The doubled 巳 turns the Snake-year branch into a visual and phonetic pun.
This is modern wordplay, not an old fixed chengyu and not a technical rule of the sexagenary cycle. Similar phrases such as “好巳连连” play on shi sounds in “good things one after another.” Their value lies in language, design, and seasonal celebration.
A chart containing Si in year, month, day, and hour positions may informally be called “four Si” or a Snake-year, Snake-month, Snake-day, Snake-hour combination. Establishing such a combination requires a stated calendar, time zone, and boundary rule. The repeated sign is a calendrical pattern rather than a universally auspicious event.
Related Earthly-Branch Terms and Common Search Confusions
- Shangsi (上巳): before the Han period, this referred to the first Si day in the first ten days of the third lunar month; the observance was later fixed on the third day of the third lunar month. It is a festival name, not Si month.
- Zi Chou Yin Mao (子丑寅卯): the first four branches are sometimes used colloquially to mean order, details, or the logic of a matter. They do not define 巳.
- Yin eats Mao’s grain (寅吃卯粮): an idiom for using future resources in advance. Its branch names express sequence, not astrology.
- “Ding is Ding, Mao is Mao” (丁是丁，卯是卯): an idiom for strict distinction and exactness. Ding is a stem and Mao is a branch; the phrase is unrelated to Si.
- Si vs. Snake: Si is the formal branch sign; Snake is its zodiac animal correspondence.
- Si month vs. the fourth lunar month: the first is often set by solar terms, while the second begins at a lunar-month boundary.
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