(grammar) a verbal conjugation class consisting of five alternating bases: -a, -i, -u, -e, and -o

(Classical Japanese grammar) a verbal conjugation class in which the verb stem ends in n-

(Classical Japanese grammar) a verbal conjugation class consisting of four alternating bases: -a, -i, -u, and -e

(grammar) The Classical Japanese bigrade verb conjugation class, consisting of the two subclasses of 上(かみ)二(に)段(だん)活(かつ)用(よう) (kami nidan katsuyō, “upper-bigrade conjugation”) and 下(しも)二(に)段(だん)活(かつ)用(よう) (shimo nidan katsuyō, “lower-bigrade conjugation”)

(linguistics, uncommon) trigrade conjugation / (informal) 3-step process

annelid

butterfly valve

a sphenoid bone

T-square

(grammar) present progressive form / (by extension, with で) making progress