trimeter (n.)youdaoicibaDictYouDict[trimeter 词源字典]
"a verse of three metrical feet," 1560s, from Latin trimetrus, from Greek trimetros "having three measures," from tri- "three" (see tri-) + metron "a measure" (see meter (n.2)). Related: Trimetrical.[trimeter etymology, trimeter origin, 英语词源]