The Collaborative International Dictionary of English v.0.48:

Low-spirited \Low"-spir`it*ed\, a.
   Deficient in animation and courage; dejected; depressed;
   dispirited; not sprightly.

   Syn: depressed, dispirited, down(predicate), downcast,
        downhearted, low.
        [1913 Webster + WordNet 1.5] -- Low"-spir`it*ed*ness,
        n.
        [1913 Webster]

WordNet (r) 3.0 (2006):

low-spiritedness
    n 1: a feeling of low spirits; "he felt responsible for her
         lowness of spirits" [syn: downheartedness,
         dejectedness, low-spiritedness, lowness,
         dispiritedness]