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