sub vs conning tower

sub and conning tower both are nouns.

Word	Noun	Adjective	Verb	Adverb
sub	Yes	No	Yes	No
conning tower	Yes	No	No	No

sub (noun)	conning tower (noun)
a submersible warship usually armed with torpedoes	a raised bridge on a submarine; often used for entering and exiting
a large sandwich made of a long crusty roll split lengthwise and filled with meats and cheese (and tomato and onion and lettuce and condiments); different names are used in different sections of the United States	an armored pilothouse on a warship

sub (verb)	conning tower (verb)
be a substitute