sudden

Từ điển American Heritage Dictionary 4th

sud·den (sŭdʹn)adj.
1. Happening without warning; unforeseen:
a sudden storm.
2. Characterized by hastiness; abrupt or rash:
a sudden decision.
See Synonyms at impetuous.
3. Characterized by rapidity; quick and swift.Idiom:all of a sudden
Very quickly and unexpectedly; suddenly. [Middle English sodain, from Old French, from Vulgar Latin *subitānus, from Latin subitāneus, from subitus, from past participle of subīre, to approach stealthily : sub-, secretly; see sub- + īre, to go; See ei- in Indo-European Roots.] sudʹden·ly adv.sudʹden·ness n.