baseballdom (1866)

“It is now our pleasing duty to particularize quite a lively game, in which the Contest and Irvington clubs took part; and here we say it was a brave thing of the first-named nine to challenge a Club whose victory over the Atlantics took all Baseball-dom by surprise.” Base-Ball: Contest vs. Irvington”. Brooklyn Eagle, August 11, 1866, p3

No earliest use given in 2009 Dickson Baseball Dictionary