monotone vs unmodulated

monotone is a noun but unmodulated is not a noun.

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

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

monotone (adjective)	unmodulated (adjective)
of a sequence or function; consistently increasing and never decreasing or consistently decreasing and never increasing in value	characterized by lack of variation in pitch, tone, or volume
sounded or spoken in a tone unvarying in pitch