速やか|すみやかsumiyaka[2]nakadaka (mid-high)

1. na-adjectivequick; speedy; prompt; rapid; swift
   決定けっていの後あとすみやかに実行じっこうに移うつして欲ほしい。↗

   I want quick action subsequent to the decision.

• Synonym迅速じんそくWrittenWritten/formal word for quickness, as in 「迅速な対応」. It stresses the speed of the action itself, while 「速やか」 stresses acting without delay.
• SynonymスピーディーCasualColloquial loanword for getting things done fast and smoothly, as in 「スピーディーな対応」. More at home in speech than 「速やか」.
• Synonym快速かいそくWrittenWritten word for high speed, or a rapid-service train, as in 「快速電車」. It points to speed itself, not to prompt handling.
• Synonym敏速びんそくWrittenWritten word for quick, agile movement, as in 「敏速な対応」. It stresses nimbleness of action rather than lack of delay.
• Synonym素早いすばやいNeutralNeutral, everyday word for quick, agile movement, as in 「素早く動く」. It stresses nimbleness of the action itself.
• Synonym早いはやいNeutralThe most general word for fast or early, as in 「足が速い」. Very common in speech; 「速やか」 is narrower and more formal.
• Related急速きゅうそくWrittenWritten word for rapid change or growth, as in 「急速に発展」. It describes how fast a process advances, not prompt responses.
• Related手早いてばやいCasualColloquial word for working quickly and deftly, as in 「手早く片付ける」. It praises brisk, skillful handling of a task.
• Related機敏きびんWrittenWritten word for alert, quick reactions, as in 「機敏な動き」. It stresses responding nimbly to a situation.
• Related手っ取り早いてっとりばやいCasualColloquial word for a quick, hassle-free way of doing something, as in 「手っ取り早い方法」. It stresses saving time and effort.
• Related早めはやめNeutralNeutral word for a little earlier than usual, as in 「早めに帰る」. It is about being ahead of schedule, not about acting immediately.
• Related簡捷かんしょうWrittenWritten word meaning quick and simple, stressing streamlined procedures. Rare in modern Japanese.
• Antonym遅いおそいNeutralAntonym: slow or late. The direct opposite of the promptness that 「速やか」 expresses.
• AntonymゆっくりNeutralAntonym: slowly, without hurrying. A common everyday word, opposite in feel to 「速やか」.
• Antonym緩慢かんまんWrittenWritten antonym: slow and sluggish, as of movement or progress. The formal opposite of 「速やか」.

Use 「速やか」 for acting without delay, as in 「速やかに避難してください」 or 「速やかな対応」; it is typical of official notices and announcements. For sheer speed of action say 「迅速」, for agility 「素早い」; the opposite is 「遅い」.

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

1. 時間じかんを置おかないこと。