The act of entering.

Permission to enter.

A door or other means of entering.

(astronomy) The entrance of the Moon into the shadow of the Earth in eclipses, or the Sun's entrance into a sign, etc.

(intransitive) To intrude or insert oneself

(transitive, US, chiefly military) To enter (a specified location or area)

(intransitive, astrology, of a planet) To enter into a zodiacal sign

(Whiteheadian metaphysics) To manifest or cause to be manifested in the temporal world; to effect ingression