noun
gremlin
GREM-lin/ˈɡremlɪn/
A real or imagined troublemaker blamed for unexplained problems.
The imaginary gremlin jams a wrench into the mechanism.

Etymology
Gremlin is of unknown origin, but its use in aviators’ slang is established: an imaginary creature took the blame for mechanical failures. The proposed connection with goblin remains uncertain.
In context
the gremlin car was indeed named after the Gremlin monster, a monster known for causing mechanical problems.
More examples
- The cartoon gremlin jammed the machine's gears.
- They joked that a gremlin had hidden the missing part.
- A persistent software gremlin delayed the launch.
Forms
gremlin · gremlins