Consonance

Consonance is the repetition of the same consonant sound in nearby words at positions other than the start, most often in the middle or at the end, producing an echo that binds a phrase without rhyming it.

The struck match caught, then went black.

The hard ck sound closes struck, match, black — and the repetition gives the line a clipped, abrupt finish that matches what it describes. That is consonance: the same consonant recurring somewhere other than the front of the word.

Where alliteration is a drumbeat at the start of words, consonance is texture spread through them. It is what makes half-rhyme possible — shape and stop, bent and burnt — which poets use where a full rhyme would be too neat and prose writers use to give a sentence a sense of closure without a chime.

The consonants carry their own character. Hard stops (k, t, p, b, d) make a line brittle and fast. Sibilants (s, sh, z) make it hiss and lengthen. Liquids (l, r, m, n) soften and slow it. Reading a passage aloud and noticing which family dominates will usually explain why it feels the way it does.

The caution is the same as for its two neighbours, and it is filed under mirror words: repetition the writer did not intend is heard as clumsiness, not as music, and only reading aloud finds it.