sinking vs immersion

sinking and immersion both are nouns.

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

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

sinking (noun)	immersion (noun)
a descent as through liquid (especially through water)	a form of baptism in which part or all of a person's body is submerged
a slow fall or decline (as for lack of strength)	the act of wetting something by submerging it
a feeling caused by uneasiness or apprehension	complete attention; intense mental effort
	sinking until covered completely with water
	(astronomy) the disappearance of a celestial body prior to an eclipse