1. The act of furnishing an equivalent person or thing in the place of another; SYN. replacing.
2. One that replaces another especially in a job or function

ETYM Cf. French subrogation, Late Lat. subrogatio.
The act of subrogating. Specifically: the substitution of one person in the place of another, such as a creditor who takes the rights of another creditor.

ETYM Latin substitutio: cf. French substitution.
1. An event in which one thing is substituted for another; SYN. permutation, transposition, replacement, switch.
2. The act of putting one one thing or person in the place of another SYN. exchange.