adj. & n.
adj. occurring or done unexpectedly or without warning; abrupt, hurried, hasty (a sudden storm; a sudden departure).
n. archaic a hasty or abrupt occurrence. all of a sudden unexpectedly; hurriedly; suddenly. on a sudden archaic suddenly. sudden death colloq. a decision in a tied game etc. dependent on one move, card, toss of a coin, etc. sudden infant death syndrome Med. = cot-death (see COT(1)). suddenly adv. suddenness n.
[ ME f. AF sodein, sudein, OF soudain f. LL subitanus f. L subitaneus f. subitus sudden ]