Turnstile (noun)

A gate consisting of rotating horizontal arms that permit passage one at a time and prevent return, especially one used for controlling access to a public building or for collecting fare at a subway station.

Origin:

Mid 19th century: from turn + stile.

Examples:

1. The turnstile was used to control the flow of people into the stadium.
2. The turnstile was equipped with a mechanism to prevent unauthorized entry.
3. The turnstile was the main point of entry for visitors to the amusement park.
4. The turnstile was part of the ticket control system at the metro station.
5. The turnstile was designed to allow one person to pass through at a time while preventing others from entering without paying.