Each entry gives the term in traditional and simplified form, its pinyin, the senses it carries in the classical corpus, the passages where it does real work, and how published translations have rendered it.
sì wéi
The four corners of the year, where the chapter says the rise and fall of cold and heat actually takes place: 夫氣之生，與其化，衰盛異也。寒暑温涼，盛衰之用，其在四維. The point is that the four seasons do not begin at their own middles but at the corners between them — 故陽之動，始於温，盛於暑；陰之動，始於清，盛於寒，春夏秋冬，各差其分 — which is why the passage can go on to a thirty-degree lag (又凡三十度也) and to a rule of treatment that has to know where the qi really is. 王冰 pins the corners to the months: spring's warmth in 辰巳, summer's heat in 午未, autumn's cool in 戌亥, winter's cold in 丑寅; 張介賓 takes 四維 as the four 季月, 辰戌丑未. The word is used a second time in the verse the chapter quotes — 謹按四維，斥候皆歸 — where the corners are the places from which the year's movement is watched.
sì shí
Where the chapter ends, and where the book's cosmology always ends: 八風四時之勝，終而復始. The seasons conquer one another in turn and begin again, and that cycle is the model for everything the chapter has said about the pulse and the colour — which is why the last clause is a warning: 逆行一過，不復可數. A season that runs backwards is not a late season, it is the end of counting. Chapter 2 built the whole regimen of the four qi on this cycle; chapter 15 uses it to close an argument about prognostics.
sì wèi
The four prohibitions that govern prescribing through the year: when the governing qi is hot, do not use what is hot; when it is cold, do not use what is cold; and the same for cool and for warm. The reason is that the year's qi is already doing that work, and adding to it overshoots. 閒氣 — the intervening qi — is treated differently: if it agrees with the governing qi, the same prohibition holds; if it does not, a small offence against it is allowed. The chapter then says what to do when one must offend: 天氣反時，則可依則及，勝其主，則可犯，以平爲期，而不可過 — treat until it is level, and stop. 四畏 is the last of the four rules the chapter gives for using the year's qi rather than fighting it.
tiān gāng
The great rope of heaven — the one cord by which the rest is gathered — and the first thing this chapter's emperor sets right before he asks anything. The image is a net: 綱 is not a law but the cord you take hold of in order to gather the net, which is why the verb is 正, to straighten, rather than 立, to establish. It is the chapter's opening claim about method: before there can be a question about two orders failing to agree, the one order has to be got straight.
tài yī tiān fú
Both agreements at once: a year that is a heaven tally — the circuit agreeing with the qi that presides above — and a year meeting — the circuit agreeing with the branch — at the same time. The chapter names it in answer to a question the base text gives without 帝曰 in front of it: 天符歲會何如？ Of the three, it is the honoured one, and the chapter grades the three as offices: the heaven tally holds the law, the year's position issues commands, and the great unity is the person himself. The severity follows the rank — struck by the holder of the law the illness is swift and perilous, by the issuer of commands slow and lingering, and by the honoured one sudden and fatal.
tài xū
The opening words of the 太始天元冊文, the document the chapter says it has been examining for ten generations, and the only cosmological image in a chapter otherwise made of arithmetic: 太虚廖廓，肇基化元. The line is one of a hymn in four-graph phrases — 萬物資始，五運終天; 布氣真靈，總統坤元; 九星懸朗，七曜周旋 — and it does what the surrounding sentences do not, which is to say that the circuits arise from somewhere. 《說文》 glosses 虛 as 大丘, a great mound: the word began as an emptied height rather than as nothing at all, which is closer to what this chapter means by it.
tiān shū
The hinge between the qi of heaven and the qi of earth, quoted from a received line: above it the qi of heaven governs, below it the qi of earth governs, and in the region between them — the meeting of the qi — the human being dwells. The chapter does not explain the hinge; it quotes it, in the 故曰 form it uses for lines already in circulation. What matters for the argument is that the hinge is in the middle, so that what is measured above and below can be read against a person standing between. The name later attaches to a stomach-channel point and to a star; neither sense is present here.
chū zhōng
The two halves of a single position of the qi: an initial thirty degrees and a remainder, and a middle that follows the same rule. They exist to divide heaven from earth — the initial is the qi of earth, the middle the qi of heaven — and they are why above and below are sought differently: 上下不同，求之亦異也. The chapter raises them in the middle of its measuring, between the step of sixty degrees and the standing of the year, and they are the smallest of the units it builds with.
jiàn qì
The qi that stands between — the one to the left and the right of the qi that governs, rather than the governing qi itself. The chapter gives it two lines and then a rule: 隨氣所在，期於左右, follow where the qi resides and look for it on the left and the right; and then 從其氣則和，違其氣則病, to follow its qi is harmony and to go against it is illness. What follows is the chapter's fullest statement of prognosis: not in one's place, shifting from place to place, losing the place one guards.
dì shì
The whole answer to the chapter's question, in four words. Asked why one disease can be treated five ways and still get better, Qibo replies that the lie of the land makes it so — the methods differ because the ground differs, not because the physicians disagree. Wang Bing unpacks it: the reference is to the generative, growing, gathering and storing of heaven and earth, and to the disposition of high and low, dry and damp. Everything that follows — east, west, north, south, centre — is this sentence unfolded.
qì jiāo
The region between the qi of heaven above and the qi of earth below, and the place the chapter assigns the human being to. It is not a boundary but a habitation: 上下之位，氣交之中，人之居也. The received line the chapter then quotes puts a hinge in the middle of it — above the heavenly pivot heaven governs, below it earth governs — and says that in the region where the qi meet, the qi of the human follows and the ten thousand things go by it. Everything the chapter has measured up to this point — the steps, the ke, the initial and the middle — is measured so that this place can be found.
yuè sǐ shēng
The moon's dying and living — 月 yuè, the moon; 死 sǐ, its waning; 生 shēng, its waxing — and the chapter uses the phrase four times as the rule that sets the number of insertions: 以月死生爲數, 以月死生爲痏數. The count is spelled out once: 月生一日一痏，二日二痏，十五日十五痏，十六日十四痏 — rising by one a day to fifteen at the full, then 漸少之 as the moon dies. It is the only arithmetic in the chapter, and it is given to exactly the complaints the chapter is about — wandering obstruction, the hip, the low back — things with no fixed place. The chapter then refuses to leave it mechanical: 用針者，隨氣盛衰，以爲痏數，針過其日數，則脱氣，不及日數，則氣不冩. The moon gives the number; the qi decides. The phrase has not appeared in any chapter transcribed on this site before.