impassible (adj.)

"incapable of feeling pain, exempt from suffering," mid-14c., from Old French impassible (13c.) or directly from Church Latin impassibilis "incapable of passion," from assimilated form of in- "not, opposite of" (see in- (1)) + passibilis "capable of passion, feeling, or suffering, from passio "suffering" (see passion). Meaning "emotionless" is from 1590s. Related: Impassibility.