Etymology From Middle English lous, lows, lowse, from Old English lūs, from Proto-West Germanic *lūs, from Proto-Germanic *lūs, from Proto-Indo-European *lewH-. Cognate with West Frisian lûs, Dutch luis, German Low German Luus, German Laus, Danish, Norwegian Bokmål, Norwegian Nynorsk, and Swedish lus, Faroese and Icelandic lús; also Welsh llau (“lice”), Tocharian B luwo, maybe Sanskrit यूका (yūkā).
1
A small parasitic wingless insect of the order Psocodea.
2
Colloquial, Dated A contemptible person; one who is deceitful or causes harm.
He said: "Thanks, friend; but you're wasting your time. You better warn Crocker. If that louse makes a play for me, he'll get hit with Chicago lightning!"1946, Joseph Thompson Shaw, The hard-boiled omnibus: early stories from Black Mask, page 388:
It's then that those louses go back to their spouses. Diamonds are a girl's best friend.1949, Diamonds Are a Girl's Best Friend (song)
2 more examples
[…] as she raised her guitar for the last loud chord, an unseen louse let loose a rubber-tipped arrow that landed right on her dark-skinned forehead.1965 December, Phil Ochs, “That Was The Year That Weren't”, in Cavalier:
After you get finished betraying all your friends, how long do you think it will be before you're all alone? You will age and die all alone. You are attractive but unloving and unlovable. You're the worst louse I have met in a long time. I hope you get what you deserve.1983 December 17, “GDMFSOB (personal advertisement)”, in Gay Community News, volume 11, number 22, page 17:
Etymology From Middle English lous, lows, lowse, from Old English lūs, from Proto-West Germanic *lūs, from Proto-Germanic *lūs, from Proto-Indo-European *lewH-. Cognate with West Frisian lûs, Dutch luis, German Low German Luus, German Laus, Danish, Norwegian Bokmål, Norwegian Nynorsk, and Swedish lus, Faroese and Icelandic lús; also Welsh llau (“lice”), Tocharian B luwo, maybe Sanskrit यूका (yūkā).
1
To remove lice from; to delouse.
There were a few wire-netted enclosures to keep young chickens from the hawks, but the fowls wandered at large, coming about the hut to ruffle their feathers in the dust, and louse themselves, and pick up scraps.1938, Norman Lindsay, Age of Consent, 1st Australian edition, Sydney, N.S.W.: Ure Smith, published 1962, →OCLC, page 108: