* A structure on a waterfront for loading and unloading ships: This is the most common meaning of "le quai".
* A platform along a railway line for passengers to board and alight from trains: This is less common, but still used in some contexts.
Here are some examples of how "le quai" can be used:
* Le quai était bondé de touristes attendant le bateau. (The dock was crowded with tourists waiting for the boat.)
* Le train a quitté le quai à 10h00. (The train left the platform at 10:00.)
* J'ai vu un chat errant sur le quai. (I saw a stray cat on the wharf.)