dysthymia Syllabification: (dys·thy·mi·a)Pronunciation: /disˈTHīmēə/Definition of dysthymia noun Psychiatry persistent mild depression. Derivatives dysthymicPronunciation: /-ˈTHīmik/ adjective & noun Origin: mid 19th century: from Greek dusthumiadysthymia in other Oxford dictionaries Definition of dysthymia in the British & World English dictionary