The state of being sudden.

plural of suddenness

Happening quickly and with little or no warning. / (obsolete) Hastily prepared or employed; quick; rapid. / (obsolete) Hasty; violent; rash; precipitate.

(poetic) Suddenly.

(obsolete) An unexpected occurrence; a surprise.

Alternative form of all of a sudden

(obsolete) all of a sudden; suddenly

plural of sudden

A tendency for processes to occur suddenly rather than gradually.

(set phrase, colloquial) Suddenly, quickly, without warning.