- any small, wingless insect of the order Anoplura (sucking louse), parasitic on humans and other mammals and having mouthparts adapted for sucking, as Pediculus humanus (body louse or head louse) and Phthirius pubis (crab louse or pubic louse).
- any insect of the order Mallophaga (bird louse, biting louse, or chewing louse), parasitic on birds and mammals, having mouthparts adapted for biting.
- plant louse.
- Slang. a contemptible person, especially an unethical one.
- to delouse.
- louse up, Slang. to spoil; botch: Miscasting loused up the movie.
Origin of louse
- any wingless bloodsucking insect of the order Anoplura: includes Pediculus capitis (head louse), Pediculus corporis (body louse), and the crab louse, all of which infest manRelated adjective: pedicular
- biting louse or bird louse any wingless insect of the order Mallophaga, such as the chicken louse: external parasites of birds and mammals with biting mouthparts
- any of various similar but unrelated insects, such as the plant louse and book louse
- plural louses slang an unpleasant or mean person
- to remove lice from
- (foll by up) slang to ruin or spoil
Word Origin and History for louse up
"parasitic insect infecting human hair and skin," Old English lus, from Proto-Germanic *lus (cf. Old Norse lus, Middle Dutch luus, Dutch luis, Old High German lus, German Laus), from PIE *lus- "louse" (cf. Welsh lleuen "louse"). Slang meaning "obnoxious person" is from 1630s. The plural lice (Old English lys) shows effects of i-mutation. The verb meaning "to clear of lice" is from late 14c.; to louse up "ruin, botch" first attested 1934, from the literal sense (of bedding), from 1931.
- Any of numerous small, flat-bodied, wingless biting or sucking insects of the orders Mallophaga or Anoplura, many of which are external parasites on humans.
Idioms and Phrases with louse up
Spoil, ruin, bungle. For example, The bad weather loused up our plans, or Your change of mind really loused me up. This slangy expression originated in World War I, when infestation with lice was the common lot of soldiers in the trenches; its figurative use dates from the 1930s.