Fast
Fast adjective - Moving, proceeding, or acting with great speed.
Usage example: the fast pace of construction resulted in our new house being done ahead of schedule
Rapid is a synonym for fast in quick topic. In some cases you can use "Rapid" instead the word "Fast" as an adjective or a noun or an adverb, when it comes to topics like speedy, hasty, hurried, swift. popular alternative
Rapid
Rapid adjective - Moving, proceeding, or acting with great speed.
Usage example: the rapid descent of the roller coaster made me feel very queasy
Fast is a synonym for rapid in quick topic. You can use "Fast" instead the word "Rapid" as an adjective or a noun or an adverb, if it concerns topics such as property, hasty, hurried, swift. popular alternative
Mutual synonyms
Both words in one sentence
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Because of this incomprehensibly rapid rotation speed, the star is actually a spheroid instead of a pure sphere, regardless of its density: That's how fast it rotates.
Source: Eldritch Location -
Improbable Aiming Skills: Luis is able to gun down two pirates who board the Abigail in rapid succession, from a fast moving speedboat, a considerable distance away, being piloted by Nick.
Source: Series / Fear the Walking Dead -
TOT Comics' entriesCatland Pounland Wars and the Smarty Lab gamesare littered with fast-moving and bullet sponging enemies that deliver rapid-fire Collision Damage from across the room.
Source: Lets Play / Gaming Garbage
Cite this Source
Rapid and Fast. (2016). Retrieved 2026, July 21, from https://thesaurus.plus/related/fast/rapid
Fast & Rapid. N.p., 2016. Web. 21 Jul. 2026. <https://thesaurus.plus/related/fast/rapid>.
Rapid or Fast. 2016. Accessed July 21, 2026. https://thesaurus.plus/related/fast/rapid.
Google Ngram Viewer shows how "fast" and "rapid" have occurred on timeline