The Collaborative International Dictionary of English v.0.48:
Egression \E*gres"sion\, n. [L. egressio.] The act of going; egress. [R.] --B. Jonson. [1913 Webster]WordNet (r) 3.0 (2006):
egression n 1: the act of coming (or going) out; becoming apparent [syn: egress, egression, emergence]