The Collaborative International Dictionary of English v.0.48:

Ingress \In"gress\, n. [L. ingressus, fr. ingredi. See
   Ingredient.]
   [1913 Webster]
   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. (Astron.) The entrance of the moon into the shadow of the
      earth in eclipses, the sun's entrance into a sign, etc.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Ingress \In"gress\, v. i.
   To go in; to enter. [R.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

ingress
    n 1: (astronomy) the disappearance of a celestial body prior to
         an eclipse [syn: ingress, immersion] [ant: egress,
         emersion]
    2: the act of entering; "she made a grand entrance" [syn:
       entrance, entering, entry, ingress, incoming]

Moby Thesaurus II by Grady Ward, 1.0:

41 Moby Thesaurus words for "ingress":
   access, adit, admission, admittance, air lock, approach, channel,
   come in, conduit, corridor, course, ditch, duct, egress, entrance,
   entranceway, entree, entry, entryway, exit, gangplank, gangway,
   go in, hall, in, ingression, inlet, intake, means of access,
   opening, passage, passageway, penetrate, trench, trough, troughing,
   troughway, tunnel, vestibule, way, way in



Bouvier's Law Dictionary, Revised 6th Ed (1856):

INGRESS, EGRESS AND REGRESS. These words are frequently used in leases to
express the right of the lessee to enter, go upon, and return from the lands
in question.