A team (plural A teams)
- (sports) The best of a set of teams in a single club.
- The A team are playing away this Saturday.
- (informal) The group or team which performs its work most effectively; a very good team.
- It looks like the A team are on duty tonight - I've never seen the hall cleared so quickly!
- (cricket, rugby) A country's reserve team or development squad, comprising the best players not selected in the national team.
- He was then selected for the South African A team before making his international debut… 
- NSW all-rounder Moises Henriques has been named captain of the Australia A team to play England in Hobart next week. 
In sports, teams are often labeled, A team, B team, C team, etc. or 1st, 2nd 3rd. In informal usage, only "A team" is used.