Any one of numerous species of small, wingless, suctorial,
   parasitic insects belonging to a tribe (Pediculina), now usually
   regarded as degraded Hemiptera. To this group belong of the lice of man
   and other mammals; as, the head louse of man (Pediculus capitis), the
   body louse (P. vestimenti), and the crab louse (Phthirius pubis), and
   many others. See Crab louse, Dog louse, Cattle louse, etc., under Crab,
   Dog, etc.