Definition of trimeter in US English:

trimeter

noun

Prosody
  • A line of verse consisting of three metrical feet.

    • ‘The number of feet per line determines the metre of a poem: if a single line contains one foot, it is called monometer, two feet is diameter, three is trimeter, etc.’
    • ‘Poems in iambic dimeters and trimeters are found in abundance in her first book, as are poems written in trochaic measure.’
    • ‘In this way of talking, the ballad stanza alternates tetrameters (four-foot lines) with trimeters (three-foot lines).’
    • ‘She will slip from dactyls to iambics, pentameter to trimeter, quatrains to sestets.’
    • ‘The regular speech-verse is the iambic trimeter.’
    • ‘Justice discovered early on a way with trimeters, whose cautious motion fit his muted resolve; pentameters took him longer to master, though by the '80s he had made them his own as well.’
    • ‘Although the English meter is properly iambic, often with feminine endings, line length is erratic, ranging from trimeter to pentameter, except for the two shortest lines, which appear in dimeter.’

Origin

Mid 16th century: via Latin from Greek trimetros, from tri- ‘three’ + metron ‘measure’.

Pronunciation

trimeter

/ˈtrimidər//ˈtrɪmɪdər/