Knucker is a dialect word for a sort of water dragon, living in knuckerholes in Sussex, England. The word comes from the Old English nicor which means "water monster" and is used in the poem Beowulf. It may also be related to the word "nixie", which is a form of water spirit, to "Old Nick", a euphemism for the devil, or to the words "Nykur", "Nickel", "Knocker", "Näcken" and "Neck", "Näkineiu" and "Näkk", and "Näkki" ."