The Collaborative International Dictionary of English v.0.48:
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
Mourning dove (Zool.), a wild dove (Zenaidura macroura)
found throughout the United States; -- so named from its
plaintive note. Called also Carolina dove. See Illust.
Mourning warbler (Zool.), 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.