In the game of cricket, innings is both singular and plural, and can apply to the team as a whole, or to an individual batter. The word inning is never used.
For example, a test match is comprised of 2 innings per team. Each team's innings is comprised of 11 individual's innings (sometimes less than 11 if there is a declaration or early victory). Thus a match may contain 4 team innings and 44 individual innings.
Occasionally, innings is used as a metaphor for a person's lifetime, as in saying of somebody who lived to an old age, "she had a good innings".