Synonyms for Cub (same or very similar meaning)
WordNet sense 1 (an awkward and inexperienced youth):
greenhorn, rookieWordNet sense 2 (a male child (a familiar term of address to a boy)):
lad, laddie, sonny, sonny boyWordNet sense 3 (the young of certain carnivorous mammals such as the bear or wolf or lion):
young carnivoreFrom the ODE community, based on WordNetadd/edit