subsidence vs abatement

subsidence and abatement both are nouns.

Word	Noun	Adjective	Verb	Adverb
subsidence	Yes	No	No	No
abatement	Yes	No	No	No

As nouns, abatement is a hypernym of subsidence; that is, abatement is a word with a broader meaning than subsidence:

subsidence: an abatement in intensity or degree (as in the manifestations of a disease)
abatement: an interruption in the intensity or amount of something

Other hypernyms of subsidence include hiatus, reprieve, respite, suspension.

subsidence (noun)	abatement (noun)
a gradual sinking to a lower level	the act of abating
the sudden collapse of something into a hollow beneath it	an interruption in the intensity or amount of something
an abatement in intensity or degree (as in the manifestations of a disease)