couwe (noun and adjective), also kowe
This term, hovering bilingually between English and French, derives from French co(u)é meaning ‘having a tail, tailed’. It doesn’t seem (according to AND or DMF) to be used in continental or insular French to refer to what we now call tail-rhyme. In his early fourteenth-century chronicle of England, the Gilbertine canon Robert Mannyng uses the phrase ‘rime couwe’, which we could transliterate as ‘tail-rhyme’, in a sequence of references to exotic types of English verse which, though impressive, may prove too complex for performance and/or copying (thus explaining his choice of simpler form). Mannyng also uses it as a noun, saying that inexperienced or incompetent readers or performers might mangle these complex verse-forms because they couldn’t join together the tails (‘couthe nat haf coppled a kowe’, kowe being a variant spelling of couwe), i.e. link up and emphasise the rhymes aurally in performance or brace/bracket them correctly on the page. The term indicates forms in which either groups of lines end with a shorter line, like a stub or tail, or that a different rhyme sound follows a pair or trio of rhymes, like a single-line ‘tail’ following a unit of lines.
The term couwe is also used as a marginal annotation later in Mannyng’s chronicle for sections which are political songs or speeches (themselves translations of tail-rhyme lyrics in Pierre de Langtoft’s Anglo-Norman Chronicle, Mannyng’s source) written in a long line which is divided into three by internal rhyme (in blue) and punctuation: e.g. ‘Whan ȝe haf þe pris . of ȝour enemys . non salle ȝe saue’ (6683). Often in these passages marked couwe, pairs of lines (and sometimes longer groups of lines) have the same rhymes in all three positions in the line, but sometimes not. Here the term couwe does not necessarily indicate that these groups of three clauses have a final clause shorter than the first two, but rather that each of these lines or groups of lines are written in the lop-sided tail-rhyme arrangement of rhymes (aab or, in other works, aaab).