c. 1200, socour, earlier socours "aid, help," from Anglo-French succors "help, aid," Old French socors, sucurres "aid, help, assistance" (Modern French secours), from Medieval Latin succursus "help, assistance," from past participle of Latin succurrere "run to help, hasten to the aid of," from assimilated form of sub "up to" (see sub-) + currere "to run" (from PIE root *kers- "to run"). Final -s mistaken in English as a plural inflection and dropped late 13c. Meaning "one who aids or helps" is from c. 1300.
late 13c., "help or relieve when in difficulty," from Old French succurre "to help, assist" (Modern French secourir), from Latin succurrere "to help, assist" (see succor (n.)). Related: Succored; succoring.