A female gremlin.
Sometimes (incorrectly?) used for all female gremlins, Fifinella was originally the name of one specific gremlin. She was created by Disney for the WASP during WWII. Her job was to scare off male gremlins.
Roald Dahl may have been the originator of the name, as he was working with Disney to create a movie about gremlins at this time.
I believe the original term for female gremlins as a class was Flipperty-Gibbets. Male gremlins are Widgets.