Source : Webster's Revised Unabridged Dictionary (1913)

Mourn \Mourn\, v. i. [imp. & p. p. {Mourned}; p. pr. & vb. n.
   {Mourning}.] [AS. murnan; akin to OS. mornian, OHG. mornen,
   Goth. ma['u]rnan.]
   1. To express or to feel grief or sorrow; to grieve; to be
      sorrowful; to lament; to be in a state of grief or
      sadness.

            Abraham came to mourn for Sarah, and to weep for
            her.                                  --Gen. xxiii.
                                                  2.

   2. To wear the customary garb of a mourner.

            We mourn in black; why mourn we not in blood?
                                                  --Shak.

            Grieve for an hour, perhaps, then mourn a year.
                                                  --Pope.

Mourning \Mourn"ing\, n. [AS. murnung.]
   1. The act of sorrowing or expressing grief; lamentation;
      sorrow.

   2. Garb, drapery, or emblems indicative of grief, esp.
      clothing or a badge of somber black.

            The houses to their tops with black were spread, And
            ev'n the pavements were with mourning hid. --Dryden.

   {Deep mourning}. See under {Deep}.

Mourning \Mourn"ing\, a.
   1. Grieving; sorrowing; lamenting.

   2. Employed to express sorrow or grief; worn or used as
      appropriate to the condition of one bereaved or sorrowing;
      as, mourning garments; a mourning ring; a mourning pin,
      and the like.

   {Mourning bride} (Bot.), a garden flower ({Scabiosa
      atropurpurea}) with dark purple or crimson flowers in
      flattened heads.

   {Mourning dove} (Zo["o]l.), a wild dove ({Zenaidura
      macroura}) found throughout the United States; -- so named
      from its plaintive note. Called also {Carolina dove}. See
      Illust. under {Dove}.

   {Mourning warbler} (Zo["o]l.), an American ground warbler
      ({Geothlypis Philadelphia}). The male has the head, neck,
      and chest, deep ash-gray, mixed with black on the throat
      and chest; other lower parts are pure yellow.

Source : WordNet®

mourning
     adj : sorrowful through loss or deprivation; "bereft of hope"
           [syn: {bereaved}, {bereft}, {grief-stricken}, {grieving},
            {mourning(a)}, {sorrowing(a)}]

mourning
     n 1: state of sorrow over the death or departure of a loved one
          [syn: {bereavement}]
     2: the passionate and demonstrative activity of expressing
        grief [syn: {lamentation}]