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.
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 man related adjective pedicular
biting louse, 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
(slang) (pl) louses. an unpleasant or mean person
to remove lice from
(foll by up) (slang) to ruin or spoil
Old English lūs; related to Old High German, Old Norse lūs
O.E. lus, "parasitic insect infecting human hair and skin," from P.Gmc. *lus (cf. O.N., M.Du., O.H.G. lus, Ger. Laur). Slang meaning "obnoxious person" is from 1630s. The plural lice (O.E. lys) shows effects of i-mutation. The verb meaning "to clear of lice" is from mid-15c.; to louse up "ruin, botch" first attested 1934.
To ruin or spill; botch; bollix up: Boy, you certainly loused that up
To fail; screw up: He'll get promoted next month if he doesn't louse up(1938+)
An obnoxious and despicable person, esp one who is devious and undependable; bastard, crumb: We kicked the dirty louse out when he said that(1633+)
The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D. Copyright (C) 2007 by HarperCollins Publishers. Cite This Source
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.