pumpkin (n.) Look up pumpkin at Dictionary.com
1640s, alteration of pompone, pumpion "melon, pumpkin" (1540s), from Middle French pompon, from Latin peponem (nominative pepo) "melon," from Greek pepon "melon," probably originally "cooked (by the sun)," hence "ripe;" from peptein "to cook" (see cook (n.)). Pumpkin-pie is recorded from 1650s. Pumpkin-head, American English colloquial for "person with hair cut short all around" is recorded from 1781. Vulgar American English alternative spelling punkin attested by 1806.
America's a dandy place:
The people are all brothers:
And when one's got a punkin pye,
He shares it with the others.
[from "A Song for the Fourth of July, 1806," in "The Port Folio," Philadelphia, Aug. 30, 1806]