n. -
Latin, literally "a
felon of himself;" a
self-murderer. Specifically, the
legal term (hence the
hifalutin Latin) for
suicide, used to describe the "crime" of suicide, in the legal sense.
To be guilty of this offense, the deceased must have had the will and intention of committing it, or else he committed no crime--the burden of proof is on the state in this case, and must be proven to a coroner and a jury. If one kills oneself inadvertently while trying to kill another, one is also guilty of felo de se, because the intent was still to murder. As the deceased is beyond the reach of human laws, he cannot be punished with fines, beatings, or imprisonment. Therefore, English law used to inflict a punishment by burial at a crossroads with a stake through one's heart, and by forfeiting to the king the property which one owned and which would have otherwise passed to one's relations. The property could usually be restored to one's family by their payment of small fees, and George IV provided for a kinder burial option--instead of mutilating the body, it simply needed to be buried at night, and privately, and could still be interred in holy ground if the felon had not committed any other mortal sins.
The charter of privileges granted by William Penn to the inhabitants of Pennsylvania contains the following clause: "If any person, through temptation or melancholy, shall destroy himself, his estate, real and personal, shall notwithstanding, descend to his wife and children, or relations, as if he had died a natural death."
Thanks to Bouvier's Law Dictionary, 1856 ed.