earworm
Pronunciation:
/ˈɪəwɜːm//ˈɪ(ə)ɹˌwɚm/noun
Definitions
A tune that keeps replaying in one's head or that one keeps thinking about, especially if unwanted.
(originally United States) Short for corn earworm (“larva of the moths Helicoverpa zea (syn. Heliothis zea) and Helicoverpa armigera, which are agricultural pests”).
An earwig.