In sports like football, soccer, or hockey, the division of the game into parts is much easier. Four quarters. Two halves. Three periods. These are divisions of the time allotted to play that particular game.
Baseball, however, is not a timed sport. Therefore, the usual segments for dividing up the game into parts don’t really work. Instead, the game is divided by aspects of play within the game itself: three outs per half-inning, with each team getting the opportunity to bat, therefore allotting six outs per full inning, and nine innings in a game. But why do we call these nine segments of the game “innings”?
Not surprisingly, the term as used in baseball originally comes from cricket, in which the time a team has at bat is referred to as an “innings.” In the original English usage of the word, “innings” was used both as the singular and the plural term. Baseball Americanized the word to create the singular “inning.”
It is interesting to note that the word “inning” pre-dates even cricket. According to the Online Etymology Dictionary, “inning” comes from the Old English word “innung,” meaning “a taking in” or “a putting in.” The first known use of “innings” in cricket occurred in 1735, referring to “a team’s turn in action in a game.” Thus, an inning refers to that period of time in a game during which a team “puts in” its time at the plate.