Nouns

(n)newcomer, fledgling, fledgeling, starter, neophyte, freshman, newbie, entrantany new participant in some activity
(n)fledgling, fledgelingyoung bird that has just fledged or become capable of flying

Adjectives

(s)fledgling, fledgeling(of a young bird) having acquired its flight feathers“a fledgling robin”