earworm

Meanings

1. A tune that keeps replaying in one's head or that one keeps thinking about, especially if unwanted.
2. Ellipsis of corn earworm (“larva of the moths Helicoverpa zea (syn. Heliothis zea) and Helicoverpa armigera, which are agricultural pests”).
3. An earwig (“insect of the order Dermaptera”).

Etymology

From ear + worm; senses 1 and 3 (“tune that keeps replaying in one’s head”; “earwig”) are a calque of German Ohrwurm (“tune that pops up in one’s memory all the time; earwig”) (from the idea of a creature burrowing into the ear, an erroneous belief where earwigs are concerned), while sense 2 (“moth larva”) refers to the fact that these pests infest, among other things, ears of maize or sweet corn.