nit (n.) Look up nit at Dictionary.com
Old English hnitu "louse egg, nit," from Proto-Germanic *hnito- (cognates: Norwegian nit, Middle Dutch nete, Dutch neet, Middle High German niz, German Niß), from PIE root *knid- "egg of a louse" (cognates: Russian, Polish gnida, Czech knida; Greek konidos, genitive konis "egg of a louse").