Lewis Short
tristĭtūdo (noun F) : id.
* Sadness, sorrow, grief, melancholy, dejection (post-class.): omnem de tuo pectore tristitudinem mitte,App. M. 3, p. 134; so id. Mag. p. 295, 19; Sid. Ep. 8, 11 fin.
Charlton T. Lewis, Charles Short, A Latin Dictionary