1. A low island or reef: "There are several keys in the West Indies, south of Florida, and in the Gulf of Mexico."

"On her trip to Florida, Susan and her family visited Key West, a small island only four miles long and two miles wide."

"The seaport, also called Key West, is the most southern city in the United States with a population of about 25,200 people."

2. Etymology: Spanish cayo, "shoal, rock"; from Arawak.