Fluke Hit (1891)

“It was hard lines indeed to have all the brilliant work of the previous innings wiped out by a ‘fluke’ hit, for fluke it was, as it was made on a bad ball that was little short of a wild pitch.” “One of the Finest Ever Played in This City,” Cincinnati Enquirer, May 4, 1891, p2

Previous earliest use (Dickson Baseball Dictionary, 3rd edition, 2009):
1901.  “[Ray] Nelson’s little infield fluke hit gave New York two runs, which, with another fluke single and two nice hits, evened up the score.” (The New York Times, June 17)