Sub″stit″ute (?), n. [L. substitutus, p. p. of substituere to put under, put in the place of; sub under + statuere to put, place: cf. F. substitut. See Statute.] One who, or that which, is substituted or put in the place of another; one who acts for another; that which stands in lieu of something else; specifically (Mil.), a person who enlists for military service in the place of a conscript or drafted man.
Hast thou not made me here thy substitute? Milton.
Ladies... wore masks as the sole substitute known to our ancestors for the modern parasol. De Quincey.