monotonic vs monotonous

monotonic and monotonous both are adjectives.

Word	Noun	Adjective	Verb	Adverb
monotonic	No	Yes	No	No
monotonous	No	Yes	No	No

As adjectives, monotonic and monotonous are synonyms defined as:

monotonic and monotonous: sounded or spoken in a tone unvarying in pitch

Other synonyms of monotonic include flat, monotone.

monotonic (adjective)	monotonous (adjective)
of a sequence or function; consistently increasing and never decreasing or consistently decreasing and never increasing in value	tediously repetitious or lacking in variety
sounded or spoken in a tone unvarying in pitch	sounded or spoken in a tone unvarying in pitch