louse

noun

1.
wingless usually flattened bloodsucking insect parasitic on warm-blooded animals
Derived from:
lousy
2.
a person who has a nasty or unethical character undeserving of respect
3.
any of several small insects especially aphids that feed by sucking the juices from plants
Derived from:
lousy
4.
wingless insect with mouth parts adapted for biting; mostly parasitic on birds
Derived from:
lousy