trimetrical
trim·e·ter
(trĭm′ĭ-tər)n.
1.
a. Verse written in lines of three metrical feet.
b. A single line of such verse.
2.
a. Classical quantitative verse consisting of three measures of two feet each, especially in iambic, trochaic, or anapestic meter.
b. A single line of such verse.
[Late Latin, from Latin trimetrus, from Greek trimetros : tri-, tri- + metron, measure; see meter1.]
tri·met′ric (trī-mĕt′rĭk), tri·met′ri·cal (-rĭ-kəl) adj.