The headword, presumably quoted from somewhere, is present participle, masculine nominative singular, of the verb nauti/llomai. Glossed likewise in other lexica (see the references at Photius nu58 Theodoridis), and cf. also a scholion on Homer, Odyssey 14.246, where the infinitive nauti/llesqai occurs (web address 1).
cf. generally nu 83, nu 85.