In baseball, a fungo bat is, according to Merriam-Webster's Eleventh Collegiate Dictionary (2003), "a long thin bat used for hitting fungoes," and a fungo is either "a fly ball hit esp. for practice fielding by a player who tosses a ball in the air and hits it as it comes down" or a "FUNGO BAT." The Eleventh Collegiate dates fungo to "ca. 1867" and fungo bat to 1926, but it reports that the origin of the word fungo is unknown.
San Francisco Giants bench coach Ron Wotus is quoted in today's Oakland Tribune discussing the bat he uses for hitting fly balls to fielders during outfield practice:
Model: Old Hickory PRO F3
Dimensions: 36 inches, 29 ounces, maple. It's a fungo! [Most game bats are 33.5 to 34.5 inches long and weigh 31 to 34 ounces.]
Upper cuts: "Can't go without the fungo! You know, I'm not sure how they got their name. I think it was in the Italian league."
But the Italian Baseball League was formed in 1948, which doesn't match well with the circa 1867 origin of the term fungo. The Wikipedia article subsection on fungo bat (part of a longer page on baseball bat) offers a different possible etymology for fungo:
The etymology of the word fungo (pronunciation: /ˈfʌŋɡoʊ/) is uncertain, but the Oxford English Dictionary suggests it is derived from the Scots fung: to pitch, toss, or fling.
However, the entries for fung in Chambers Scots Dictionary (1911) are less baseball-friendly than the Wikipedia/OED treatment might suggest:
Fung, v. to strike, beat; to kick; to throw with force; to anger; to annoy, offend; to work briskly; to work in a temper; to lose one's temper; to give forth a sharp, whizzing sound.—n. a blow, thrust, kick; a 'bang' out, the pet, a fit of bad temper. —adv. violently, with a 'whiz'.
Fung, n. beer.
Fung about, v. to drive hither and thither at high speed.
I have three questions about fungo as used in U.S. baseball:
What is the source of the word fungo?
When was fungo in the sense of "a fly ball" first recorded in print?
How (if at all) has the word's meaning changed since it was coined?