ingress (n.) Look up ingress at Dictionary.com
mid-15c., from Latin ingressus "an advance; walking; an entry," from ingress-, past participle stem of ingredi "to step into, enter," from in- "in" (from PIE root *en "in") + gradi "to step, go" (see grade (n.)). The verb meaning "to enter, go in" sometimes said to be American English, but it is attested from early 14c.