turnstile

Meaning

Noun

• 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.
• The $\backslash vdash$ 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)". )

Origin

• turn + stile
• Image:Turnstiles in Alewife station, August 2005.jpg|A set of turnstiles in the USA|right|thumb|190px