The vocabulary, defined once
Twelve terms carry almost every Bazi reading you will read. Each one below gets a short definition you can hold in your head, a table where the term has one, and a link to the long-form page that applies it.
Most explanations of Chinese astrology assume the vocabulary and then use it quickly. A reader meets 日主 in one paragraph, 十神 in the next, and 大运 three lines later, with no pause to say what any of them are. This page is the pause.
Each entry is deliberately short. A definition that runs to two thousand words is not a definition, it is an article, and it is harder to check. These are the sentences you would want if you had to explain a term to somebody in a lift, with the full treatment linked underneath.
Where a term has a table attached, the table is here rather than in the article. The ten stems, the twelve branches, the hidden stems, and the full grid of the ten gods are all fixed by the tradition or derived from it by arithmetic, so they can be printed once and checked.
The twelve terms
Grouped the way a reading is built: the ideas first, then the chart, then what is read out of it.
Foundations
Bazi (八字)
八字 · bā zì
Bazi (八字, bā zì, "eight characters") is the Chinese method of writing a birth moment as eight characters: four pillars, each made of one heavenly stem and one earthly branch, taken from the year, month, day, and hour of birth.
Yin and Yang (陰陽)
陰陽 · yīn yáng
Yin and yang are two labels for how a pair of things stand to each other at a given moment: yin for the cooler, darker, slower, more contracted side of the pair, and yang for the warmer, brighter, faster, more expansive one.
The Five Elements (五行)
五行 · wǔ xíng
The five elements (五行, wǔ xíng) are Wood, Fire, Earth, Metal, and Water, read as five phases of a cycle rather than five kinds of matter. Each one produces the next and controls another, so the set is a system of relationships rather than a list.
The Ten Heavenly Stems (天干)
天干 · tiān gān
The ten heavenly stems (天干, tiān gān) are a fixed sequence of ten characters, 甲 乙 丙 丁 戊 己 庚 辛 壬 癸, that label the top half of every pillar in a Bazi chart. They are the five elements doubled: each element appears once in a yang form and once in a yin form.
The Twelve Earthly Branches (地支)
地支 · dì zhī
The twelve earthly branches (地支, dì zhī) are the fixed sequence 子 丑 寅 卯 辰 巳 午 未 申 酉 戌 亥. Each one carries a zodiac animal, a season, an element, and a two-hour window of the day, and each sits underneath a heavenly stem in a pillar.
Building the chart
The Four Pillars (四柱)
四柱 · sì zhù
The four pillars (四柱, sì zhù) are the year, month, day, and hour of birth, each written as one heavenly stem over one earthly branch. They are not four separate readings. The day pillar is the reference point, and the other three are interpreted in relation to it.
Day Master (日主)
日主 · rì zhǔ
The day master (日主, rì zhǔ, also written 日元) is the heavenly stem of the day pillar, the character that stands for the person the chart describes. Every other character in the chart is read as a relationship to it, which is why it is fixed first and never changes.
Month Command (月令)
月令 · yuè lìng
The month command (月令, yuè lìng) is the earthly branch of the month pillar. It records the season a person was born into, and in most schools it carries more weight than any other single character, because the season decides which element is in charge.
Hidden Stems (藏干)
藏干 · cáng gān
Hidden stems (藏干, cáng gān) are the one to three heavenly stems stored inside each earthly branch. A branch is not a single element: 子 holds only 癸, while 寅 holds 甲, 丙, and 戊, which is how a chart carries more information than its eight visible characters.
Reading the chart
The Ten Gods (十神)
十神 · shí shén
The ten gods (十神, shí shén) are the ten ways a heavenly stem can stand to the day master. Which one applies is fixed by two things: which of the five element relations holds between the two stems, and whether they share a polarity. The names describe relationships, not deities.
Luck Pillars (大運)
大運 · dà yùn
Luck pillars (大運, dà yùn) are the ten-year cycles that follow a Bazi chart through life. Each one is a stem and branch pair, and each changes which elements are in play on top of the chart's eight fixed characters.
True Solar Time (真太陽時)
真太陽時 · zhēn tài yáng shí
True solar time (真太陽時, zhēn tài yáng shí) is the time read from the sun at the birth location rather than from a clock. It differs from clock time by up to about two hours, and Bazi uses it for the hour pillar, so two charts from the same clock minute can differ.
Twelve terms, one system
These are the words a Bazi reading is built from. The audit takes the same idea in a different direction: which corner of the room you are standing in.
Where these definitions come from
- The tables are the standard ones. The ten stems, the twelve branches with their animals and hours, and the hidden stems inside each branch are the same in any Chinese almanac, and you can check any row of them against a printed one.
- The ten gods are computed rather than copied. Two rules generate the whole ten by ten grid: which way the element runs between two stems, and whether the two share a polarity. The page renders the table from those rules at build time, so it cannot drift from the definition above it.
- Dates, where a term depends on one, come from an ephemeris rather than from memory. The February boundary on the month command page is the actual moment of Start of Spring in 2027, generated with a calendar library rather than recalled.
- Where a term is contested, the page says so. Whether the day pillar turns at 23:00 or midnight is a live disagreement between schools, and the entries say that instead of picking a side quietly.
Questions people ask about the glossary
Do I need to know all twelve terms to read a chart?
No. Four will carry you through most readings: the day master, the ten gods, the five elements, and the four pillars. The rest are what you reach for when a reading turns on a detail, such as which stem is hidden inside a branch or how the luck pillars step.
Are these entries the same as the articles on the blog?
They overlap on purpose and split the work. These are the wiki layer, short definitions meant to be quotable. The articles are the long layer, where a topic gets its evidence, its examples, and its numbers. Each entry links to the articles that carry its topic further.
Which term should I read first?
Bazi, then the four pillars, then the day master. Those three establish what a chart is and which character in it stands for the person. The ten gods and the luck pillars make far more sense once you know what they are measured against.
Can I check these tables against another source?
Yes, and you should. The stems, the branches, and the hidden stems are identical in every almanac, so any disagreement means one of the sources has a typo. The ten gods grid can be verified by hand from the two rules, and the arithmetic is printed on that page.
Why is there no entry for feng shui or the I Ching?
Because this glossary covers the vocabulary of the birth chart, which is one system. Feng shui and the I Ching are separate systems with their own terms, and mixing them into one list is how a reader ends up thinking a compass direction and a day master are the same kind of thing.
This page has no affiliate links and nothing to sell. The tables here are fixed by the tradition and you can check any of them against a printed almanac. What a chart means for a person is a reading of that tradition, not a finding, so treat it as a way to think about a situation rather than a prediction.