decrease vs sinking

decrease and sinking both are nouns.

Word	Noun	Adjective	Verb	Adverb
decrease	Yes	No	Yes	No
sinking	Yes	No	No	No

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

Other hyponyms of decrease include shrinkage, shrinking, casualty, attrition, rarefaction, dwindling, dwindling away, waning.

decrease (noun)	sinking (noun)
the act of decreasing or reducing something	a descent as through liquid (especially through water)
the amount by which something decreases	a slow fall or decline (as for lack of strength)
a change downward	a feeling caused by uneasiness or apprehension
a process of becoming smaller or shorter

decrease (verb)	sinking (verb)
decrease in size, extent, or range
make become smaller