How to say "hastily" in Japanese

• 急遽きゅうきょCommon
  adverbCovers acting hurriedly or in haste when something unexpected forces quick action. Nuance of emergency urgency; typical when plans must be changed or arranged at the last minute.
• さっさとJLPT N2approx.Common
  adverbMatches the brisk, prompt sense of hastily — doing something quickly and without delay. Mildly mimetic in tone; fits getting a task over with promptly rather than acting under sudden pressure.
  さっさと宿題しゅくだいをしなさい。↗

  Do your homework without delay.
• 急にきゅうにJLPT N3approx.Common
  adverbBest for the sudden-change sense: something happening swiftly or abruptly rather than someone acting hastily. It is really an adverb of suddenness, so it is seldom the word you want for hasty deliberate action.
  気苦労きぐろうで彼かれは急きゅうにふけた。↗

  Care aged him quickly.

急遽 emphasizes acting with sudden urgency, 「さっさと」 emphasizes brisk speed and promptness, and 「急に」 chiefly describes sudden change rather than hasty action, so reserve it for suddenness.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 急遽きゅうきょhurriedly
• さっさとquickly
• 急にきゅうにswiftly
• あたふたin a hurry
• そそくさhurriedly