humdrum vs prosaic

humdrum is a noun but prosaic is not a noun.

Word	Noun	Adjective	Verb	Adverb
humdrum	Yes	Yes	No	No
prosaic	No	Yes	No	No

As adjectives, humdrum and prosaic are synonyms defined as:

Other synonyms of humdrum include commonplace, unglamorous, unglamourous.

humdrum (noun)	prosaic (noun)
the quality of wearisome constancy, routine, and lack of variety

humdrum (adjective)	prosaic (adjective)
tediously repetitious or lacking in variety	not challenging; dull and lacking excitement
not challenging; dull and lacking excitement	lacking wit or imagination
	not fanciful or imaginative