for-tu-i-tous / fôr-to͞o-ĭ-təs, fôr-tyo͞o-ĭ-təs
1. accidental; happening by chance, often with a favorable outcome
The plague as we of today have the happiness to know it is merely Nature’s fortuitous manifestation of her purposeless objectionableness.
Ambrose Bierce, 1842 – 1914
2. lucky; having or bringing good fortune
Just how I was to help Perry I could scarce imagine, but I hoped that some fortuitous circumstance might solve the problem for me.
From “At the Earth’s Core” by Edgar Rice Burroughs, 1875 – 1950
From the Latin adjective fortuitus, fortuita, fortuitum (by chance, accidental, random) derived from the Latin feminine noun fors, fortis (chance, accident, luck).
Thank you to Allen Ward for providing this etymology of fortuitous.