level rod . A straight rod or bar, with a flat face graduated in plainly visible linear units with zero at the bottom, used in measuring the vertical distance between a point on the Earth's surface and the line of sight of a leveling instrument that has been adjusted to a horizontal position. It is usually made of metal or well-seasoned wood. See also: target rod; self-reading leveling rod. Syn: rod [surv]; leveling rod; surveyor's rod.