submarine

A boat that can go underwater.

A kind of sandwich made in a long loaf of bread.

Pitch delivered with an underhand motion.

Any submarine plant or animal.

A stowaway on a seagoing vessel.

To operate or serve on a submarine.

To torpedo; to destroy with a sudden sneak attack.

(sometimes figurative) To sink or submerge oneself.

Undersea.

Hidden or undisclosed.

“a submarine patent”

Of a pitch, thrown with the hand lower than the elbow.