- a post with revolving horizontal bars, placed in an entrance to allow the passage of persons but not of horses, cattle, etc.
- a similar apparatus, often coin-operated, used to admit persons one at a time
- A mechanical device used to limit the passage of individuals moving from one public area to another to one at a time, consisting of a vertical post or frame with several bars that project from it and revolve at the same point, with the bar in the highest position being parallel to the floor.
- A similar structure that permits the passage of an individual once a charge has been paid or that counts the number of individuals passing through.
- A rotating mechanical device that controls and counts passage between public areas, especially one that only allows passage after a charge has been made.
- (mathematics, logic, proof theory) The symbol used to represent logical entailment (deducibility relation), especially of the syntactic type, i.e., syntactic consequence. (Such symbol can be read as "proves". )
- Comma-separated elements preceding the turnstile should be interpreted as forming a conjunction, whereas comma-separated elements following the turnstile should be interpreted as forming a disjunction.
- (mathematics, logic): double turnstile