From Latin 'deprimere' (to press down) — the physical act of pushing downward became the psychology of lowered spirits.
To push down or lower; to make sad or gloomy; to reduce the level or strength of something, especially economic activity.
From Old French 'depresser,' from Late Latin 'depressare,' a frequentative of Latin 'deprimere' (to press down), composed of 'de-' (down) and 'premere' (to press). The literal sense 'to press down physically' came first; the psychological meaning 'to make sad' developed by the early seventeenth century, drawing on the metaphor of spirits being pushed or weighed down. The economic sense
The Great Depression (1929-1939) gave the word 'depression' its most powerful modern association. Before that, economic downturns were typically called 'panics' (the Panic of 1837, the Panic of 1893). President Hoover reportedly preferred 'depression' because it sounded less alarming than 'panic' or 'crisis' — an irony, given how ominous the word became.