Fortuitous

Adjective

 * 1) Happening by chance; coincidental or accidental.
 * 2) Happening by a lucky chance; lucky or fortunate.
 * 3)  Happening independently of human will.

Adverbs for Fortuitous
curiously; obviously; luckily; presumably; casually; wholly; comically; inexplicably; mysteriously; admittedly; ludicrously; certainly; providentially; frequently; purportediy; evidently; luckily; awkwardly; pleasantly; tragically; undependably; uneasily; uncertainly; opportunely; ironically; favorably; conveniently.

Synonyms for Fortuitous
fortunate, contingent, incidental, random, accidental, casual, chance.

Antonyms for Fortuitous
deliberate, rehearsed, plotted, planned, arranged, calculated.

Derived terms

 * fortuitously
 * fortuitousness

Thesaurus
accessory, accidental, additional, adscititious, adventitious, aleatory, appurtenant, ascititious, auxiliary, casual, causeless, chance, chancy, circumstantial, collateral, contingent, destinal, dicey, extra, fatal, fatidic, fluky, iffy, incidental, indeterminate, inessential, nonessential, odd, risky, secondary, subsidiary, superadded, superfluous, supervenient, supplemental, supplementary, uncaused, undetermined, unessential, unexpected, unforeseeable, unforeseen, unlooked-for, unpredictable