for·tu·i·tous event /fȯr-'tü-ə-təs-, -'tyü-/ n: an event of natural or human origin that could not have been reasonably foreseen or expected and is out of the control of the persons concerned (as parties to a contract): force majeure – called also cas fortuit; see also frustration compare inevitable accident
Merriam-Webster’s Dictionary of Law. Merriam-Webster. 1996.