droning vs monotone

droning and monotone both are nouns.

Word	Noun	Adjective	Verb	Adverb
droning	Yes	No	No	No
monotone	Yes	Yes	No	No

As nouns, droning and monotone are synonyms defined as:

Other synonyms of droning include drone.

droning (noun)	monotone (noun)
an unchanging intonation	an unchanging intonation
	a single tone repeated with different words or different rhythms (especially in rendering liturgical texts)

droning (adjective)	monotone (adjective)
	of a sequence or function; consistently increasing and never decreasing or consistently decreasing and never increasing in value
	sounded or spoken in a tone unvarying in pitch