Source : Webster's Revised Unabridged Dictionary (1913)

Unlucky \Un*luck"y\, a.
   1. Not lucky; not successful; unfortunate; ill-fated;
      unhappy; as, an unlucky man; an unlucky adventure; an
      unlucky throw of dice; an unlucky game.

   Note: This word is properly applied to incidents in which
         failure results from chance or fortuity, as in games of
         hazard, rather than from lack or feebleness of effort.

   2. Bringing bad luck; ill-omened; inauspicious.

            Haunt me not with that unlucky face.  --Dryden.

   3. Mischievous; as, an unlucky wag. [Colloq.]

Source : WordNet®

unlucky
     adj 1: having or bringing misfortune; "Friday the 13th is an
            unlucky date" [syn: {luckless}] [ant: {lucky}]
     2: marked by or promising bad fortune; "their business venture
        was doomed from the start"; "an ill-fated business
        venture"; "an ill-starred romance"; "the unlucky prisoner
        was again put in irons"- W.H.Prescott [syn: {doomed}, {ill-fated},
         {ill-omened}, {ill-starred}]