early 15c., "adherent, partisan," agent noun from support (v.). Meaning "that which supports" is from 1590s.
Entries linking to supporter
support v.
late 14c., "to aid," also "to hold up, prop up, put up with, tolerate," from Old French suporter "to bear, endure, sustain, support" (14c.), from Latin supportare "convey, carry, bring up, bring forward," from assimilated form of sub "up from under" (see sub-) + portare "to carry," from PIE root *per- (2) "to lead, pass over." Related: Supported; supporting.