What is the X in X-mas?
1721, "loss of feeling," Modern Latin, from Greek anaisthesia "want of feeling, lack of sensation (to pleasure or pain)," from an- "without" (see an- (1)) + aisthesis "feeling," from PIE root *au- "to perceive" (see audience). As "a procedure for the prevention of pain in surgical operations," from 1846.
anesthetist a·nes·the·tist (ə-něs'thĭ-tĭst)
A person trained to administer anesthetics.