bunk vs subject matter

bunk and subject matter both are nouns.

Word	Noun	Adjective	Verb	Adverb
bunk	Yes	No	Yes	No
subject matter	Yes	No	No	No

As nouns, subject matter is a hypernym of bunk; that is, subject matter is a word with a broader meaning than bunk:

Other hypernyms of bunk include content, message, substance.

bunk (noun)	subject matter (noun)
a bed on a ship or train; usually in tiers	content communicating a message; what something is about
a rough bed (as at a campsite)
beds built one above the other
a long trough for feeding cattle
unacceptable behavior (especially ludicrously false statements)
a message that seems to convey no meaning

bunk (verb)	subject matter (verb)
flee; take to one's heels; cut and run
provide with a bunk
avoid paying