Happening by accident or chance. See Synonyms at accidental.(adjective)
Usage Problem Happening by a fortunate accident or chance.(adjective)
Usage Problem Lucky or fortunate.(adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "fortuitous" in a sentence
"Hence there grew up the belief that events which we describe as fortuitous or random or subject to chance are no different from any other happenings, except that we do not know why they happen."
"For very many in the world attribute everything to themselves and their prudence, and what they cannot so attribute they call fortuitous and accidental, not knowing that human prudence is nothing and that "fortuitous" and "accidental" are idle words."
"The reliance on coincidence or the fortuitous is often questionable, but the results at the same time are never quite incredible."