ear-worm

Noun

earworm (plural earworms)

1. A tune that keeps replaying in one's head or that one keeps thinking about, especially if unwanted.
   • The chorus [of "Meeting in the Ladies Room" by Klymaxx] spawned an earworm so potent that women still mutter it as they exit for a bathroom break twenty years later.2005, “Klymaxx: Meeting in the Ladies Room (Constellation, 1984)”, in Kim Cooper, David Smay, editors, Lost in the Grooves: Scram’s Capricious Guide to the Music You Missed, New York, N.Y....

   Synonyms:

   brainworm

2. (archaic) An earwig; an insect of the order Dermaptera.
   • Earwig, [...] The ear-worm or grub, a well-known insect, with large transparent wings, which eats fruit and flower-leaves, and has been erroneously supposed to creep into the human brain through the ear; [...]1865, John Ogilvie, “Earwig”, in The Student’s English Dictionary, Etymological, Pronouncing, & Explanatory: […], London; Edinburgh: Blackie and Son, […], →OCLC, page 270, column 2