mid-14c., oppressioun, "cruel or unjust use of power or authority," from Old French opression (12c.), from Latin oppressionem (nominative oppressio) "a pressing down; violence, oppression," noun of action from past-participle stem of opprimere "press against, press together, press down;" figuratively "crush, put down, subdue, prosecute relentlessly" (in Late Latin "to rape"), from assimilated form of ob"against" (see ob-) + premere "to press, hold fast, cover, crowd, compress" (from PIE root *per- (4) "to strike").
Meaning "action of weighing on someone's mind or spirits" is from late 14c. Sense of "whatever oppresses or causes hardship" is from late 14c. In Middle English also "rape."
updated on September 04, 2019