Felo de Se
The act of a suicide when he commits self-murder. Murder is felony, and a man who murders himself commits this felony —felo de se.
“A felo-de-se, therefore, is he that deliberately puts an end to his own existence.” —Blackstone: Commentaries, book iv. chap. xiv. p. 189.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894