Synonyms of the word 
FORTUITOUS → CAUSELESS - FORTUNATE - UNCAUSED - UNINTENDED
fortuitous
- adj. Happening by chance; coincidental or accidental.
- adj. Happening by a lucky chance; lucky or fortunate.
- adj. (law) Happening independently of human will.
causeless
- adj. Having no obvious cause; fortuitous or inexplicable.
- adj. groundless or unreasonable.
fortunate
- adj. Happening by good luck or favorable chance.
- adj. Bringing unforeseen positives.
- adj. Presaging happiness.
- adj. Auspicious.
- adj. Lucky, favored by fortune.
uncaused
- adj. spontaneous, unintended and uninitiated.
unintended
- adj. Not intended; unplanned.
If you are interested in words, visit the following sites :
- wiktionary.org/fortuitous For complete definition of a word
- 1word.ws/fortuitous to play with words, suffixs, prefixs, etc.