coot

Etymology 1

From Middle English cote, coote, cute, cuytt (“coot”), of uncertain origin. Perhaps from an unrecorded Old English word, or borrowed from Middle Dutch coet, cuut, kuut (“coot”) (whence modern Dutch koet and meerkoet (“coot”)). Possibly related to Middle High German kūz, kūze (modern German Kauz (“owl”)), Old English cȳta (“kite, bittern”) (whence English kite), ultimately from Proto-Germanic *kūts (“bird of prey”). See kite.

noun

1. Any of various aquatic birds of the genus Fulica that are mainly black with a prominent frontal shield on the forehead.
2. (colloquial) A foolish or eccentric fellow
   A silly coot
   An old coot
   A rich coot
   “You'll be able now to give it as your considered opinion that [Wilbert Cream] is as loony as a coot, Sir Roderick.” A pause ensued during which [the psychiatrist] appeared to be weighing this, possibly thinking back to coots he had met in the course of his professional career and trying to estimate their dippiness as compared with that of W. Cream. 1960, P. G. Wodehouse, Jeeves in the Offing, chapter VII
3. (slang, with the) A success; something excellent.
   Man that song's the coot.
   Would be the coot if we could go this weekend!

Etymology 2

Compare cootie.

noun

1. (slang) Body louse (Pediculus humanus).