1.  ingress(n = noun.event) immersion - (astronomy) the disappearance of a celestial body prior to an eclipse;
is a kind of disappearance
is a part of eclipse, occultation
Antonym: egress

2.  ingress(n = noun.act) entering, entrance, entry, incoming - the act of entering; "she made a grand entrance"
is a kind of arrival
has particulars: incursion, intrusion, irruption, entree, enrollment, enrolment, registration, penetration, admission, admittance

1.  The act of entering; entrance; as, the ingress of air into the lungs. [1913 Webster]

2.  Power or liberty of entrance or access; means of entering; as, all ingress was prohibited. [1913 Webster]

3.  The entrance of the moon into the shadow of the earth in eclipses, the sun's entrance into a sign, etc. [1913 Webster]

   To go in; to enter. [1913 Webster]

ingress, n.
1 the act or right of going in or entering.
2 Astron. the start of an eclipse or transit.

Derivative:
ingression n.

Etymology:
ME f. L ingressus (as INGREDIENT)

N  ingress, entrance, entry, introgression, influx, intrusion, inroad, incursion, invasion, irruption, ingression, penetration, interpenetration, illapse, import, infiltration, immigration, admission, insinuation, insertion, inlet, way in, mouth, door, barway, path, conduit, immigrant, incoming.

VB  have the entree, enter, go into, go in, come into, come in, pour into, pour in, flow into, flow in, creep into, creep in, slip into, slip in, pop into, pop in, break into, break in, burst into, burst in, set foot on, ingress, burst in upon, break in upon, invade, intrude, insinuate itself, interpenetrate, penetrate, infiltrate, find one's way into, wriggle into, worm oneself into, give entrance to, insert.

N  passage, transmission, permeation, penetration, interpenetration, transudation, infiltration, endosmose exosmose, endosmosis, intercurrence, ingress, egress, path, conduit, opening, journey, voyage, passing, intercurrent, endosmosmic, endosmotic, en passant.