無痛 is read as むつう (mutsuu) and means painless.
むつう
mutsuu
むつうぶんべん
obstetric analgesia during labor and delivery (e.g. epidural)
つうかいむひ
very thrilling
むじん
shorthandedness
むちゃ
rash
むりやり
forcibly
むり
impossible
むりょう
free (of charge)
ぶじ
good health
むしょく
without an occupation
むごん
silence (not speaking)
むせん
radio (communication)
むよう
unnecessary