slip_away
1. [ verb ] leave furtively and stealthily
Synonyms: sneak_off steal_away sneak_out leave_quietly sneak_away
Examples:

"The lecture was boring and many students slipped out when the instructor turned towards the blackboard"

Related terms: leave
2. [ verb ] pass by, as of time
Synonyms: pass go_by elapse go_along glide_by slip_by slide_by lapse
Related terms: advance fly lapse
Similar spelling:   slipway
  slip_by