Толковый словарь английского языка Oxford English Reference - nit

1. n. 1 the egg or young form of a louse or other parasitic insect esp. of human head-lice or body-lice. 2 Brit. sl. a stupid person. Phrases and idioms nit-pick colloq. indulge in nit-picking. nit-picker colloq. a person who nit-picks. nit-picking n. & adj. colloq. fault-finding in a petty manner. Etymology: OE hnitu f. WG 2. int. Austral. sl. used as a warning that someone is approaching. Phrases and idioms keep nit keep watch; act as guard. Etymology: 19th c.: orig. unkn.: cf. NIX(3)