tail-rhyme

tail-rhyme,
translated from the Latin rhythmus caudatus, the measure associated in particular with a group of Middle English romances in which a pair of rhyming lines is followed by a single line of different length and the three-line pattern is repeated to make up a six-line stanza. Chaucer's ‘Sir Thopas’ (see Canterbury Tales , 17) is an example; six are edited by M. Mills in Six Middle English Romances ( 1973 ).