Fast
Fast adjective - Acting or moving or capable of acting or moving quickly.
Usage example: fast film
Instant
Instant adjective - Done or occurring without any noticeable lapse in time.
Usage example: an instant response to the cry for help
Fast is a synonym for instant in immediate topic. Sometimes you can use "Fast" instead an adjective "Instant", if it concerns topics such as ready-made, pre-prepared.
Mutual synonyms
Both words in one sentence
- He had an instant death attack, but the chances of it succeeding were very low, he cast it infrequently, and after a certain point he died too fast for this to be an issue.
Source: Peninsula of Power Leveling -
If you're fast enough, you can actually get to the room before they take cover; small help considering that they'll be on alert the instant you try anything on them.
Source: That One Level -
Proto-Seeker is fast-firing weapon with homing projectiles and instant target lock, drains very little energy, but it's heavy, has a short lock-on range, eats lots of CPU and does very little damage.
Source: Videogame / Robocraft
Cite this Source
Instant and Fast. (2016). Retrieved 2026, July 21, from https://thesaurus.plus/related/fast/instant
Fast & Instant. N.p., 2016. Web. 21 Jul. 2026. <https://thesaurus.plus/related/fast/instant>.
Instant or Fast. 2016. Accessed July 21, 2026. https://thesaurus.plus/related/fast/instant.
Google Ngram Viewer shows how "fast" and "instant" have occurred on timeline