stability vs monotony

stability and monotony both are nouns.

Word	Noun	Adjective	Verb	Adverb
stability	Yes	No	No	No
monotony	Yes	No	No	No

As nouns, monotony is a hyponym of stability; that is, monotony is a word with a more specific, narrower meaning than stability:

Other hyponyms of stability include invariance, metastability.

stability (noun)	monotony (noun)
the quality or attribute of being firm and steadfast	the quality of wearisome constancy, routine, and lack of variety
the quality of being enduring and free from change or variation	constancy of tone or pitch or inflection
a stable order (especially of society)