Meaning & use

instantaneous

adjective·Advanced

Occurring or done immediately, without any perceptible delay.

See it in a sentence

His reaction to the loud noise was instantaneous, and he ducked before it even registered.

The new software offers nearly instantaneous search results across millions of documents.

A note on using this word

Instantaneous is more formal and technical than 'instant,' and is common in scientific or precise descriptions of speed.

Words with a similar meaning

immediateinstant

Choose a synonym to suit the sentence. Meanings can overlap without being identical.

Words with an opposite meaning

delayedgradual

Make it your own

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