inning

Etymology 1

Back-formation from innings, mistaken to be plural of the time period, not the entries of the batters/batsmen.

noun

1. (baseball) A period of play in which members of a visiting baseball team attempt to hit a baseball pitched by the opposing home team until three players are called out, followed by a similar attempt by members of the home baseball team against the visiting team's pitching. There are nine or more innings in a regulation baseball game.
   It is a baseball tradition to sing "Take Me Out To the Ball Game" during the seventh inning stretch.
2. (softball) A similar period of play.
   We batted around in our half of the inning.
3. (billiards) A player (or team)'s turn at the table to make shots until ended by a miss or a foul.
4. A chance or opportunity to perform some deed or act.
   We are in just the second inning of our quest to enter this new market.
5. (obsolete) The gathering of a crop; harvesting.
   […] for the mowing, reaping, shering, getting or inning of corne, […] 1563, Richarde Jugge, Anno Quinto Reginae Elizabethe
6. (obsolete) Lands recovered from the sea.
   One of the earliest ‘innings’ of Walland Marsh, after the Norman Conquest,‥has been ever since called Becket's Innings, as this Archbishop has the credit of promoting it. 1880, Archaeologia Cantiana

Etymology 2

verb

1. present participle and gerund of inn