1630s, "taking the place of another," from Latin vicarius "that supplies a place; substituted, delegated," from vicis "a change, exchange, interchange; succession, alternation, substitution," from PIE root *weik- (2) "to bend, to wind."
From 1690s as "done or experienced in place of another" (usually in reference to punishment, often of Christ); from 1929 as "experienced imaginatively through another." Related: Vicariously.