Ingress

ingress \ˈin-ˌgres\ noun: 1. the act of entering; entrance {the seal prevents ingress of moisture},
2. the power or liberty of entrance or access {an area with restricted ingress}

Etymology: Middle English, from Latin ingressus, from ingredi to go into, from in- + gradi to go

NINE — Over time voiding waste shed its old taboo connotations and came to be viewed as an act of purification. After all, it stands to reason that if ingesting food is self-pollution, then ridding the body of that matter is cleansing.