Other forms: rookies
A rookie is someone who's new at something. The young football player who's just joined the NFL is a rookie, and if you just started your restaurant job yesterday, you're a rookie too.
Police officers and members of the military also call recent recruits rookies. This word can also function as an adjective to describe something related to newbies — like a "rookie season" or a "rookie quarterback." The word's origin is a bit hazy, though it may come from the disparaging secondary meaning of rook, "a cheat," or more appropriately, "someone who's easily cheated."