faster; fastest
1 : with great speed
The boss expects this to be done this afternoon, so you'd better work fast.
You're driving too fast!
He ran as fast as he could.
a fast-paced story
: in a very short time : very quickly
This is fast becoming a national problem.
You need to act fast to take advantage of this offer.
species that are fast disappearing = species that are disappearing fast
I don't know what caused the accident. It all happened so fast.
2 a : in a quick and intelligent way
She's a woman who can think fast in a crisis.
You catch on fast.
b : quickly and in a way that is meant to deceive or persuade someone
He's going to have to talk fast to get himself out of this mess.
— see also FAST-TALK
3 : in a way that is not easily moved or changed
The window was stuck fast.
She held fast to her belief in justice.
We must stand fast and not surrender!
fast and furious
— see FAST
fast asleep
— see ASLEEP
going/getting nowhere fast informal
◊ To be going/getting nowhere fast is to be failing to make progress or to produce a desired result.
The plan for a new stadium is going nowhere fast.
not so fast informal
— used in speech to say that you disagree with what someone has said or to tell someone to stop or slow down
“This proves they're wrong.” “Not so fast. There's other evidence to consider.”
“The discussion is closed.” “Not so fast. I have a few more things to say.”