in·vo·lu·tion·al I. \|invə|lüshənəl, -shnəl also -vəl|yü-\adjective Etymology:involution + -al 1.: of or relating to involutional melancholia < involutional depression > 2.: of or relating to the climacterium and its associated bodily and psychic changes < mental hygiene in the involutional time of life > II. noun (-s) : one that suffers from involutional melancholia