Synonyms for sudden

modified

sudden implies extreme quickness or hastiness and, usually, unexpectedness a sudden outburst of temper; precipitate adds the implication of rashness or lack of due deliberation a precipitate decision; abrupt implies an unexpected break coming without warning, often unceremoniously taken aback by his abrupt departure and it may suggest a curtness of speech an abrupt dismissal; impetuous implies vehement impulsiveness or extreme eagerness an impetuous suitor

all of a sudden