Sigmund Freud likened the state of melancholia to mourning in his 1917 paper "Mourning and Melancholia".
Although "melancholia" remained the dominant diagnostic term, "depression" gained increasing currency in medical treatises and was a synonym by the end of the century; German psychiatrist Emil Kraepelin may have been the first to use it as the overarching term, referring to different kinds of melancholia as "depressive states".