fungo (n.)
"A fly ball hit to a player during fielding practice in which the batter (often a coach) tosses the ball into the air and hits it as it descends with a long and narrow bat." [Paul Dickson, "The Dickson Baseball Dictionary," 3rd ed., 2009], attested from 1867 (fungoes), baseball slang, of unknown origin; see Dickson's book for a listing of the guesses. Perhaps from a Scottish fung "to pitch, toss, fling;" perhaps from some dialectal fonge "catch," a relic of Old English fon "seize" (see fang), or possibly from the German cognate fangen. Not in OED 2nd ed. (1989). There does not seem to have been a noun phrase (a) fun go in use at the time. It formally resembles the Spanish and Italian words for "fungus."
Dictionary entries near fungo
fungi
fungible
fungicide
fungiform
fungivorous
fungo
fungous
fungus
funicular
funipendulous
funk