Meaning of “fast” - Learner’s Dictionary

fast

adjective uk us /fɑːst/
QUICK

A1 moving, happening, or doing something quickly:

fast cars
a fast swimmer
Computers are getting faster all the time.
TIME [ never before noun ]

If a clock or watch is fast, it shows a time that is later than the correct time:

My watch is five minutes fast.
→ See also a fast track (to sth)

(Definition of “fast adjective” from the Cambridge Learner’s Dictionary © Cambridge University Press)