IPA: /ˌæntɪdɪˈprɛʃən/
KK: /æntiˈdɛprɪʃən/
Relating to something that helps to prevent or counteract feelings of sadness or economic downturns.
The antidepression measures implemented by the government helped boost the economy.
Antidepression is formed from "anti-" (meaning against) and "depression" (from Latin "depressio", meaning a pressing down or lowering). The word refers to measures or treatments that work against depression or alleviate its effects.
Think of 'against' ('anti-') something that is 'pressing down' ('depression') — that's why antidepression means working against feelings of being pressed down or sad.