adjective / adverb
fast
FAST/fæst/
Moving or happening quickly.
The fast cheetah stretches into a powerful running stride across the grass.

Etymology
Old English fæst meant “firm, secure.” The speed sense may have developed through “strongly, vigorously,” as running hard means running fast, or through the image of a runner sticking close to a target.
In context
Many of you have been telling me that you struggle to hear Chinese tones in fast speech.
More examples
- She runs faster than anyone on the team.
- We need to act fast before the water rises.
- That was the fastest repair I have ever seen.
Forms
fast · faster · fastest
fast-paced adjective — Moving or changing very quickly