- \ \  Etymologically, a tour is a ‘circular movement’. The word comes via Old French tour from Latin tornus ‘lathe’, which also produced English turn. It was not used for a ‘journey of visits’ – literally a ‘circuitous journey’ – until the 17th century (the term grand tour, denoting a lengthy journey around western Europe formerly undertaken by fashionable young men, ostensibly for educational purposes, is first recorded in the mid-18th century, but the derivative tourist does not crop up until about 1800). Tournament  and tourney  both go back ultimately to a Vulgar Latin derivative of tornus, the underlying etymological notion being of the combatants ‘turning’ or wheeling round to face each other. And tourniquet  probably comes from the same source.\ \ Cf.⇒ TOURNAMENT, TOURNIQUET, TURN
Word origins - 2ed. J. Ayto. 2005.