trimeter
noun/ˈtrɪmɪtə(r)/, /ˈtraɪmɪtə(r)/
/ˈtrɪmɪtər/
(specialist)- a line of poetry consisting of three sets of syllables called feet
三角仪：由三组称为脚的音节组成的诗歌行 Word Originmid 16th cent.: via Latin from Greek trimetros, from tri- ‘three’ + metron ‘measure’.