1. the spiral shell of a gastropod, often used as a horn.
2. any of various marine gastropods.
3. the fabled shell trumpet of the Tritons.
4. (often initial capital letter) Slang (sometimes disparaging). a. a native or inhabitant of the Florida Keys.
b. a Bahamian.
5. Also, concha. Architecture. a smooth concave surface consisting of or resembling the interior of a semidome, as the surface of a vault, a trompe, or the head of a niche.