Definition from Wiktionary, the free dictionary
innings (plural innings)
- (baseball) Plural form of inning
- (cricket) One side's or individual's turn to bat (from when the first player begins to bat, until the last player is out,) or the runs scored during those timeframes.
- (UK) The time during which any party is in possession of power; a turn of any kind.
Usage notes 
In British English, innings is used for both singular and plural; inning is not heard (except in connection with baseball).