ingress

Short definition from Wiktionary

Noun

1. 1
   The act of entering.
2. 2
   A permission to enter.
3. 3
   A door or other means of entering.
4. 4
   The entrance of the Moon into the shadow of the Earth in eclipses, or the Sun's entrance into a sign, etc.

Verb

1. 1
   To intrude or insert oneself
2. 2
   To enter (a specified location or area)
3. 3
   To enter into a zodiacal sign
4. 4
   To manifest or cause to be manifested in the temporal world; to effect ingression

Proper noun

1. 1
   A surname.