n. 1 Brit. hist. the sum of 21 old shillings ($1.05), used esp. in determining professional fees. 2 hist. a former British gold coin worth 21 shillings, first coined for the African trade. guinea-fowl any African fowl of the family Numididae, esp. Numida meleagris, with slate-coloured white-spotted plumage. guinea-pig 1 a domesticated S. American cavy, Cavia porcellus, kept as a pet or for research in biology etc. 2 a person or thing used as a subject for experiment.
[ Guinea in W. Africa ]