deadening vs ho-hum

deadening is a noun but ho-hum is not a noun.

Word	Noun	Adjective	Verb	Adverb
deadening	Yes	Yes	No	No
ho-hum	No	Yes	No	No

As adjectives, deadening and ho-hum are synonyms defined as:

deadening and ho-hum: so lacking in interest as to cause mental weariness

Other synonyms of deadening include boring, dull, irksome, slow, tedious, tiresome, wearisome.

deadening (noun)	ho-hum (noun)
the act of making something futile and useless (as by routine)

deadening (adjective)	ho-hum (adjective)
so lacking in interest as to cause mental weariness	so lacking in interest as to cause mental weariness