(1):

(n.) One who boils.

(2):

(n.) A strong metallic vessel, usually of wrought iron plates riveted together, or a composite structure variously formed, in which steam is generated for driving engines, or for heating, cooking, or other purposes.

(3):

(n.) A vessel in which any thing is boiled.

(4):

(n.) A sunken reef; esp., a coral reef on which the sea breaks heavily.