Source : Webster's Revised Unabridged Dictionary (1913)

Assassination \As*sas`si*na"tion\, n.
   The act of assassinating; a killing by treacherous violence.

Source : WordNet®

assassination
     n 1: an attack intended to ruin someone's reputation [syn: {character
          assassination}, {blackwash}]
     2: murder of a public figure by surprise attack