ingress vs immersion

ingress and immersion both are nouns.

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

As nouns, ingress and immersion are synonyms defined as:

ingress and immersion: (astronomy) the disappearance of a celestial body prior to an eclipse

ingress (noun)	immersion (noun)
the act of entering	a form of baptism in which part or all of a person's body is submerged
(astronomy) the disappearance of a celestial body prior to an eclipse	the act of wetting something by submerging it
	complete attention; intense mental effort
	sinking until covered completely with water
	(astronomy) the disappearance of a celestial body prior to an eclipse