sub vs breather

sub and breather both are nouns.

Word	Noun	Adjective	Verb	Adverb
sub	Yes	No	Yes	No
breather	Yes	No	No	No

sub (noun)	breather (noun)
a submersible warship usually armed with torpedoes	air passage provided by a retractable device containing intake and exhaust pipes; permits a submarine to stay submerged for extended periods of time
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	a short respite

sub (verb)	breather (verb)
be a substitute