- 1圓周率（符號 π）
Pi is a number. You write it with the Greek letter π. For any circle, if you take the distance all the way round (the ) and divide by the distance across through the centre (the diameter), you get the same number: pi. It is a little more than 3.14, and the digits after the point go on for ever without a repeating pattern. School maths uses 3.14 or 22/7 as a stand-in; the real number never ends. The name comes from the Greek letter, and that letter was taken because it begins the Greek word for the rim, the periphery, of a circle. A Welsh teacher, William Jones, is first known to have used π this way in a book in 1706. In English the word is spoken like pie. It is ordinary in maths class and in any talk about circles.
From the word’s history
From the Greek letter πῖ; its use in mathematics apparently comes from the first letter of περιφέρεια 'circumference' (1706, William Jones).
希臘字母 π；數學用法可能取自希臘文「圓周」一字的字首。
組成From the Greek letter π (pi), itself from an older name of that letter, and in the end from a Semitic word for “mouth.” Maths took the letter because it starts Greek periphereia, the line around a circle. It is a doublet of the letter-name pe.
原始詞典資料32 筆記錄
以下是外部詞典記錄的用法，摘錄並精簡格式，我們還沒有寫成教學內容。上面的說明才是我們自己寫的；有些用法可能上面已經講過了。
Piname
- 1
historicalA county of Chengdu, Sichuan, China.
- Pi County has brought democracy into full play. The peasants there are electing production team leaders and other production team cadres by secret ballot.
- [...]water carriers, the sedanchair carriers, the pawn brokers, and even the manure collectors in a market town in Pi county, Szechwan in the late Ch'ing period.
pinoun詞源 1/paɪ/
- 1
The sixteenth letter of the Classical and Modern Greek alphabets and the seventeenth in Old Greek.
- 2
mathematicssciencesAn irrational and transcendental constant representing the ratio of the circumference of a Euclidean circle to its diameter; approximately 3.14159265.
pinoun詞源 2
- 1
letterpress-typographymediapublishingMetal type that has been spilled, mixed together, or disordered.
piverb詞源 2
- 1
letterpress-typographymediapublishingTo spill or mix printing type.
piadj詞源 2
- 1
mediapublishingtypographyNot part of the usual font character set; especially, non-Roman type or symbols as opposed to standard alphanumeric Roman type.
- In computing, pi characters may be entered with special key combinations.
pinoun詞源 3
- 1
mediapublishingtypographypica (conventionally, 12 points = 1 pica, 6 picas = 1 inch).
- 2
Piaster.
piadj詞源 3
- 1
Pious.
- Our Major was "Cherub" Cheeseman, noted for his foul language. I am afraid he lost a tidy little legacy that he was expecting from his aunt, the Dowager Lady Shuttlecock (a very "pi" old lady), through this same habit of his.
- “Those are very 'pi' sentiments. Was a preacher in Staffordshire— I was raised chapel, though've tried to forget it—he talked that way... redemption and the lot.”
這個拼法也被記錄為下列字的變化形：
- Piauí
- Prison Industries
- Philippine Islands
- politically incorrect
- processing instruction
- partial induction
- personal injury
- principal investigator
- private investigator
- parallel import
- phosphatidylinositol
- protease inhibitor
- polyimide
- ponderal index
- penile inversion
- power integrity
- prohibited immigrant
- pseudoincest
- port injection
- paradoxical intention
- pro forma invoice
- people's initiative
- preliminary injunction
摘錄自 英文維基詞典 English Wiktionary，已精簡格式；依 CC BY-SA 4.0 授權使用，改動後的內容同樣以此授權提供。