it looks like all the various guinea names trace back to the name of the region in west africa (oddly, this historical map shows a region called "guinea" that doesn't contain any of the countries that currently have "guinea" in their name). according to wiki, the origin of the name "guinea" is as follows:
The name comes from the Berber term "aginaw" via Portuguese; it originally meant "black" (or, in context, "land of the blacks.")which brings me to another thing i've wondered about: how many countries in africa have a name that arguably comes from the color of the inhabitant's skin? by my count, it's six: guinea, guinea-bissau, equatorial guinea, mauritania, sudan and ethiopia. some probably think there are two more, niger and nigeria, but those two are named after the niger river whose name, in turn, probably comes from the tuareg phrase "gher n gheren" ("river of rivers"), shortened to "ngher". so i'm sticking with six.
i don't know if any other continent has even a single country name relating to the racial characteristics of the people living there.
ADDING: aaron points out in the comments that lesotho, and possibly somalia, also have race-based etymologies. and it also occurred to me that tanzania should also half count. that country was created out of the confederation of the british colony of tanganyika and the british protectorate of zanzibar. the name "tanzania" is the combination of the two words. "zanzibar" means "coast of the blacks." so the count now stands at 8.5. all but lesotho and somalia are names that are derived from outsider's languages.
