(telegraphy) straight key

a surname

(mahjong) determining what tile would complete an opponent's hand

a depressor labii inferioris

The way to distinguish an olive flounder from a righteye flounder. 鮃(ひらめ) (hirame, “olive flounder”) can be distinguished from 鰈(かれい) (karei, “righteye flounder”) by noting that the eyes of the former are on the left and the eyes of the latter are on the right.

(linear algebra) upper triangular matrix

(grammar) an abbreviation for 上二段活用; upper dual grade conjugation

(grammar) Short for 上一段活用 (kami ichidan katsuyō): upper monograde conjugation

Alternative spelling of お手上げ: throwing up one's hands: giving up, quitting

(mahjong) drawing the winning tile off the dead wall after declaring a 槓 (kan, “kong”), worth 1 翻 (han, “double”)