Definition of “sudden” - Learner’s Dictionary

sudden

adjective us uk /ˈsʌdən/
Extra Examples
With a sudden jolt the train started moving again.He put on a sudden burst of speed.The stories in the newspaper brought her career to a sudden end.She was hit by a sudden wave of nausea.The silence was broken by a sudden knock at the door.

B2 done or happening quickly and unexpectedly:

a sudden change/increase
His sudden death was a great shock to us all.
all of a sudden

B2 unexpectedly:

All of a sudden she got up and walked out.
suddenness noun [ U ]

(Definition of “sudden” from the Cambridge Learner's Dictionary © Cambridge University Press)