This is the 717th most frequent Persian word.
سریع
Fast.
Here, 'سریع' is used as an adjective to describe the noun 'دونده' (runner), depicting quickness or speed.
او یک دونده سریع است.
He is a fast runner.
In this sentence, 'سریع' is employed adverbially to describe how the action of 'deciding' should be carried out, implying it should be done quickly.
باید سریع تصمیم بگیریم.
We need to decide quickly.
Here, 'سریع' acts as an adjective to qualify the noun 'ماشین' (car), indicating that the car is capable of swift movement or operation.