short piece of sacred choral music, typically polyphonic and unaccompanied. late Middle English: from Old French, diminutive of mot 'word'. moth n. (pl. moths ) a chiefly nocturnal insect related to the butterflies. It lacks the clubbed antennae of butterflies and typically has a stout body, drab coloration, and wings that fold flat when resting. Most superfamilies of the order Lepidoptera. Formerly placed in a grouping known as the Heterocera. INFORMAL short for CLOTHES MOTH. like a moth to the flame with an irresistible attraction for someone or something: