depress (v.)

late 14c., "put down by force, conquer," a sense now obsolete, from Old French depresser "to press down, lower," from Late Latin depressare, frequentative of Latin deprimere "press down," from de "down" (see de-) + premere "to press, hold fast, cover, crowd, compress" (from PIE root *per- (4) "to strike").

Meaning "push down physically, press or move downward" is from early 15c.; that of "deject, make gloomy, lower in feeling" is from 1620s; economic sense of "lower in value" is from 1878.