Japanese

Noun

パイ ‎(romaji pai)

1. pie (type of pasty), tart

Etymology 2

Borrowing from English pi.^[1][2]

Some dictionaries^[3] state that this derives from the Greek name for the letter π ‎(p). However, this name is pronounced /pi/ in Greek, and /paɪ/ in English. A derivation directly from Greek is thus very unlikely.

Noun

パイ ‎(romaji pai)

1. pi, the Greek letter π

   Used in mathematics to represent the constant of the ratio of the circumference of a circle to its diameter (3.14159265...), or to represent a product of a multiplication operation.

References

1. 1 2 3 2006, 大辞林 (Daijirin), Third Edition (in Japanese), Tōkyō: Sanseidō, ISBN 4-385-13905-9
2. 1 2 1997, 新明解国語辞典 (Shin Meikai Kokugo Jiten), Fifth Edition (in Japanese), Tōkyō: Sanseidō, ISBN 4-385-13143-0
3. 1 2 1988, 国語大辞典（新装版） (Kokugo Dai Jiten, Revised Edition) (in Japanese), Tōkyō: Shogakukan