turnstile

/ˌtʌrnˈstaɪl/

/ˈtʌnstaɪl/

Other forms: turnstiles

A gate that only lets one person at a time pass through is a turnstile. After you swipe your subway card, you can move through the turnstile into the station.

Turnstiles are used to control and restrict people who are entering an area like a train station or office building. Many turnstiles are used in places where an entry fee is required. Two people can't fit through a turnstile at once, so they are also used to keep an accurate count of how many people pass through. The earliest turnstiles were used by shepherds, allowing them to exit a pen while keeping sheep inside.

Definitions of turnstile

1. noun

   a gate consisting of a post that acts as a pivot for rotating arms; set in a passageway for controlling the persons entering
   type of:

   gate

   a movable barrier in a fence or wall