TURNSTILE

turnstile

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

Source: WordNet® 3.1

Etymology

Noun

turnstile (plural turnstiles)

A rotating mechanical device that controls and counts passage between public areas, especially one that only allows passage after a charge has been paid.

A similar device in a footpath to allow people through one at a time while preventing the passage of cattle.

(mathematics, logic) The $$\vdash$$ symbol used to represent logical entailment (deducibility relation), especially of the syntactic type; i.e, syntactic consequence. (Such symbol can be read as "prove(s)" or "give(s)". )

Source: Wiktionary

Turn"stile`, n.

1. A revolving frame in a footpath, preventing the passage of horses or cattle, but admitting that of persons; a turnpike. See Turnpike, n., 1.

2. A similar arrangement for registering the number of persons passing through a gateway, doorway, or the like.

Source: Webster’s Unabridged Dictionary 1913 Edition