guinea (n.) Look up guinea at Dictionary.com
former British coin, 1660s, from Guinea, region along the west coast of Africa, presumably from an African word (perhaps Tuareg aginaw "black people"); the 20-shilling coins so called because they were first minted for British trade with Guinea (but soon in domestic use) and with gold from Africa. The original guinea (in use from 1663 to 1813) was based on the value of gold and by 1695 it was worth 30 shillings. William III then fixed its value at 21 shillings, 6 pence in 1698. The extra 6 pence were lopped off in December 1717.

The Guinea hen (1570s) is a domestic fowl imported from there. Guinea "derogatory term for Italian" (1896) was originally Guinea Negro (1740s) and meant "black person, person of mixed ancestry." It was applied to Italians c.1890 probably because of their dark complexions relative to northern Europeans, and after 1911 was occasionally applied to Hispanics and Pacific Islanders as well. New Guinea was so named 1546 by Spanish explorer Inigo Ortiz de Retes in reference to the natives' dark skin and tightly curled hair.