The Collaborative International Dictionary of English v.0.48:

Felo-de-se \Fe"lo-de-se`\, n.; pl. Felos-de-se. [LL. felo, E.
   felon + de of, concerning + se self.] (Law)
   One who deliberately puts an end to his own existence, or
   loses his life while engaged in the commission of an unlawful
   or malicious act; a suicide. --Burrill.
   [1913 Webster]