资料来源 : Webster's Revised Unabridged Dictionary (1913)

Mournful \Mourn"ful\, a.
   Full of sorrow; expressing, or intended to express, sorrow;
   mourning; grieving; sad; also, causing sorrow; saddening;
   grievous; as, a mournful person; mournful looks, tones, loss.
   -- {Mourn"ful*ly}, adv. -- {Mourn"ful*ness}, n.

   Syn: Sorrowful; lugubrious; sad; doleful; heavy; afflictive;
        grievous; calamitous.

资料来源 : WordNet®

mournfulness
     n : a state of gloomy sorrow [syn: {sorrowfulness}, {ruthfulness}]