Black tuxedo jacket and matching trousers. Formal (piquÃ© or pleated front) white shirt. Shirt studs and cuff links. Black bow tie (silk, satin, or twill) Black cummerbund to match tie, or a vest. Dressy braces to ensure a good fit (optional) No gloves. Black patent shoes and black dress socks.
GCIDE(0.00 / 0 votes)Rate this definition: 1  Datum(n.) a single piece of information; a fact; especially a piece of information obtained by observation or experiment; -- used mostly in the plural. 2  Datum(n.) (Surveying) a point, line, or level surface used as a reference in measuring elevations. RHUD.
Quick Answer. A datum line is a point of reference or standard for comparison. The term is primarily used in reference to surveying and engineering, where it is used in the measurement of depths and heights.