Envelope rhyme

Envelope (enclosed) rhyme is a way of joining lines by the scheme abba, when the first line rhymes with the fourth and the second with the third, as if the outer pair "encloses" the inner one. Such a structure creates a closed, concentrated sound of the stanza, in which the outer lines frame the central ones, emphasising their semantic connection. Envelope rhyme lends the quatrain intonational completeness and a particular harmonious integrity, and it is therefore often used in meditative, philosophical lyric and in canonical forms, notably in the quatrains of the Italian sonnet. Together with adjacent and alternate rhyme, envelope rhyme completes the triad of basic schemes for organising rhyme in the quatrain.