unforeseen (adj.)
- abrupt
- accidental
- adventitious
- aleatory
- casual
- causeless
- chance
- chancy
- contingent
- dicey
- electrifying
- extraordinary
- fatal
- fluky
- fortuitous
- hasty
- headlong
- iffy
- impetuous
- improbable
- impulsive
- incidental
- indeterminate
- out-of-the-way
- precipitant
- precipitate
- precipitous
- quick
- risky
- shocking
- speedy
- startling
- sudden
- surprising
- swift
- unannounced
- unanticipated
- uncaused
- undetermined
- unexpected
- unforeseeable
- unheralded
- unlooked-for
- unpredictable
- unpredicted
- unsought
