gremlin

noun5

1. •
   An imaginary creature reputed to be mischievously inclined, for example, to damage or dismantle machinery.

   • Crucial time was saved by the fact Nexus didn't require a Transport & Works Act. Nevertheless, other gremlins kept raising their heads. — 2023
2. •
   Any mysterious, unknown source of mischief or trouble, or the problem created thereby.

   • We rechecked everything, and we suspect gremlins in the database.
3. •
   A person regarded as similar to a fictional gremlin, in particular: mischievous, troublesome, short, or annoying.
4. •
   (slang) A young, inexperienced surfer or skateboarder, regarded as a nuisance.
5. •
   (no longer used) A contemptible person.