Choose the perfect synonym or antonym for the word

Instant

/ˈɪnst(ə)nt/

Something that takes place or can be done immediately and requires no delay.

Synonyms:

'That instant,' said Ralph.

Blunt nodded in instant comprehension.

The next instant he subsided into his old state.

Originating in the early 15th century from the Latin instans, meaning present, urgent, derived from instare, meaning to be pressing.

12 mentions per 1 million words

Moderate

Hint: Frequency according to COCA