The Collaborative International Dictionary of English v.0.48:
Painless \Pain"less\, a. Free from pain; without pain. -- Pain"less*ly, adv. -- Pain"less*ness, n. [1913 Webster]WordNet (r) 3.0 (2006):
painlessly adv 1: without pain; "after the surgery, she could move her arms painlessly" [ant: painfully, sorely]