late 14c., "to check, restrain," from Latin repressus, past participle of reprimere "hold back, curb," figuratively "check, confine, restrain, refrain," from re- "back" (see re-) + premere "to press, hold fast, cover, crowd, compress" (from PIE root *per- (4) "to strike").
Used of feelings or desires from late 14c.; in the purely psychological sense, it represents German verdrängen (Freud, 1893), first attested 1904 (implied in repressed). Meaning "to put down" (a rebellion, etc.) is from late 15c. Related: Repressed; repressing.