In baseball why is an inning called an inning?

Answer:
Some word origin authorities claim it comes from the term describing the period of time a team is "in play" or "in the field." So, an inning is that part of the game when each team has their turn at being "in the field."
First answer by David Rogoff. Last edit by Cyberdadstl. Contributor trust: 18 [recommend contributor recommended]. Question popularity: 2 [recommend question].