gauge
A standard dimension, quantity, or amount, such as a) the width between the rails of a railroad track; types include narrow gauge, standard gauge, broad gauge; b) the dimaeter of wire; c) the thickness of sheet metal; d) the distance between centers of rows of bolts or rivets; or e) a mixture of ingredients, such as gauge mortar, gauged stuff. See also gauged, gauge pile. 2. The exposed portion of an installed slate, tile, or similar element. 3. An indicator of a physical condition, such as a steam pressure gauge or a gauge glass. 4. An instrument for determining dimensions, capacity, quantities, or forces. 5. The distance between the inside faces of the heads of the rails in a track. (Bucher, 1996)