1.Definition: (of a photographic lens or emulsion) causing a shortening of exposure time
"A fast lens"
2.Definition: (of surfaces) conducive to rapid speeds
"A fast road", "Grass courts are faster than clay"
3.Definition: (used of timepieces) indicating a time ahead of or later than the correct time
"My watch is fast"
4.Definition: acting or moving or capable of acting or moving quickly
"Fast film", "On the fast track in school", "Set a fast pace", "A fast car"
5.Definition: at a rapid tempo
"The band played a fast fox trot"
7.Definition: resistant to destruction or fading
9.Definition: unrestrained by convention or morality
10.Definition: unwavering in devotion to friend or vow or cause