A louse (Pediculus humanus).
Any germ or contaminant, real or imagined, especially from the opposite gender (for pre-pubescent children).
A sideswiper, a type of telegraph key.
A nest-building female American coot (counterpart to cooter).
Any destructive insect that attacks crops or livestock; an agricultural pest.
An animal regarded as a nuisance, destructive, or a parasite, vermin.
An annoying person, a nuisance.
An invasive weed.