Why was "tantrum" trending last week?
in the modern sense, 1845, American English, from base (n.) + ball (n.1). Earlier references, e.g. in Jane Austen's "Northanger Abbey," refer to the game of "rounders," of which baseball is a more elaborate variety. Legendarily invented 1839 by Abner Doubleday in Cooperstown, N.Y. Base was used for "start or finish line of a race" from 1690s; and the sense of "safe spot" found in modern children's game of tag can be traced to 14c. (the sense in baseball is from 1868).