noun: (countable, Michigan, Northwest Indiana, derogatory) Acronym of fucking Illinois people; chiefly used by year-round inhabitants of tourist towns: a tourist to southwestern Michigan or northwestern Indiana lakeshore towns from the Chicago area; especially a wealthy such tourist.
noun: (uncountable, veterinary medicine) Acronym of feline infectious peritonitis. [(veterinary medicine) An uncommon but usually fatal cat disease caused by an aberrant immune response to infection with feline coronavirus (FCoV).]