Synonyms for Nipper (same or very similar meaning)
WordNet sense 1 (a young person of either sex):
child, fry, kid, minor, nestling, shaver, tike, tyke, youngster, tiddler, small fryWordNet sense 2 (a grasping structure on the limb of a crustacean or other arthropods):
claw, pincer, chelaFrom the ODE community, based on WordNetadd/edit