pain·less /ˈpenləs/ 形容詞
Pain·less a. Free from pain; without pain. -- Pain*less*ly, adv. -- Pain*less*ness, n.
adj 1: requiring little hard work or exertion; "a painless solution
to the problem"
2: not causing physical or psychological pain; "painless
dentistry" [ant: painful]
3: with as little pain as possible; "a humanely painless