Fortuitous

google

ref

mid 17th century: from Latin fortuitus, from forte ‘by chance’, from fors ‘chance, luck’.

wiktionary

ref

From Latin fortuītus.

etymonline

ref

fortuitous (adj.)

1650s, from Latin fortuitus "happening by chance, casual, accidental," from forte "by chance," ablative of fors "chance" (related to fortuna; see fortune). It means "accidental, undesigned" not "fortunate." Earlier in this sense was fortuit (late 14c.), from French. Related: Fortuitously; fortuitousness.