louse in WordNet English dictionary

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