(an instrument used for measuring) the thickness of wire, sheets of metal, rubber on a tyre etc; the distance between rails for a train (or between opposite wheels of a train)

measure, standard

a variable factor in an analysis or experiment

limit

a plan of action, statement of aims and ideals, e.g. one made by a government, political party, business company etc

procedure, tactics

a rule or guide for behaviour

law, rule of behavior, action

an order, law or custom which guides or controls behaviour or action; a habit; authority; to govern (people, a country etc)

standard, principle of behavior

a standard used for comparison

gauge