tail-rhyme (noun)

This term is not used in Middle English, though the term rime couwe is an early fourteenth-century Anglo-Norman equivalent of this modern term.  Rhiannon Purdie in her recent study of this form, Anglicising Romance: Tail-rhyme and Genre in Medieval English Literature (D S Brewer, 2008), gives the following definition of the modern critical term tail-rhyme: ‘The term “tail-rhyme” […] describes a stanza that repeats an aa(a)b rhyme pattern throughout, whether it is isometric (lines of the same length) or heterometric (lines of varying length), and whether the a-rhyme is retained for the whole stanza (aabaabaabaab) or changes (aabccbddbeeb).  That medieval scribes recognised both isometric and heterometric forms as “tail-rhyme” is indicated by the fact that scribes of Anglo-Norman and Middle English texts would copy both types in a distinctive layout developed for tail-rhyme stanzas.’ (p. 14)

Purdie notes that it is asymmetry (i.e. that a group of lines sharing a rhyme, a bit like a body, is followed by a single line, a bit like a tail, which does not rhyme with them) rather than line-length (i.e. that the non-rhyming line is a tail because it is shorter) which is the key characteristic defining tail-rhyme:  ‘The fundamental feature of a tail-rhyme stanza is that it is built up from asymmetric units rhyming aab or sometimes aaab’. (p. 4)