EARWORM

Etymology

Noun

earworm (plural earworms)

A tune that keeps replaying in one's head or that one keeps thinking about, especially if unwanted.

(originally, US) Short for corn earworm (“larva of the moths Helicoverpa zea (syn. Heliothis zea) and Helicoverpa armigera, which are agricultural pests”).

(archaic) An earwig (“insect of the order Dermaptera”).

Source: Wiktionary