抑郁症
yì yù zhèng · HSK 7
clinical depression
抑 suppress + 郁 gloom + 症 medical condition = a diagnosed, suppressed-gloom illness
症 is the suffix for a named medical condition (as in 癌症 cancer). 抑郁 on its own is the adjective gloomy/depressed; adding 症 turns the mood into the clinical diagnosis. The yì-yù sound pair also chimes, which helps the two halves stick together.