unplanned

1 happening by chance an unplanned change in our itinerary—we got lost! Synonyms casual, chance, fluky (also flukey), fortuitous, inadvertent, incidental, unintended, unintentional, accidental, unpremeditated, unwittingRelated Words coincidental; freak, odd; aimless, arbitrary, desultory, haphazard, random; uncertain, unexpected, unforeseeable, unforeseen; coerced, forced, involuntary; unconscious, unpromptedNear Antonyms certain, destined, expected, fixed, foreordained, foreseeable, foreseen, inevitable, predestined, predetermined, predictable, preordained, prescribed, sure; conscious, freewill, knowing, unforced, voluntary, volunteer, willful (or wilful)Antonyms calculated, deliberate, intended, intentional, planned, premeditated, premeditative, prepense, set

2 made or done without previous thought or preparation stumbled through a completely unplanned acceptance speech Synonyms ad hoc, ad-lib, down and dirty, extemporary, extempore, impromptu, improvisational, improvised, offhand, offhanded, off-the-cuff, snap, spur-of-the-moment, unconsidered, extemporaneous, unpremeditated, unprepared, unrehearsed, unstudiedRelated Words unscripted; automatic, impulsive, instinctive, involuntary, spontaneous; casual, cursive, informal, unauthorized; half-baked, half-cocked, ill-advisedNear Antonyms deliberate, intended, intentionalAntonyms considered, planned, premeditated, premeditative, prepared, rehearsed