1. Happening by chance; coming or occuring unexpectedly, or without any known cause; chance; as, the fortuitous concourse of atoms. It was from causes seemingly fortuitous . . . That all the mighty effects of the reformation flowed. (Robertson) So as to throw a glancing and fortuitous light upon the whole. (Hazlitt)
2. Happening independently of human will or means of foresight; resulting from unavoidable physical causes.
Synonym: accidental, casual, contingent, incidental. See accidental.
Origin: L. Fortuitus; akin to forte, adv, by chance, prop. Abl. Of fors, fortis, chance. See Fortune.