"something superlative," 1809, American English, agent noun from ding (v.). Baseball sense of "a home run" is by 1984.
Entries linking to dinger
ding v.
1819, "to sound as metal when struck," possibly abstracted from ding-dong (1550s), which is of imitative origin. The meaning "to deal heavy blows" is c. 1300, probably from Old Norse dengja "to hammer," perhaps also imitative. Meaning "dent" is 1960s. Related: Dinged; dinging.
humdinger n.
1883, American English, probably from dinger, an early 19c. slang word for anything superlative; also see hummer.