ordnance datum
noun
mean sea level calculated from observation taken at Newlyn, Cornwall, and used as the official basis for height calculation on British mapsAbbreviation: OD
Nearby words
ordinary-language philosophy, ordinate, ordination, ordn., ordnance, ordnance datum, ordnance survey, ordo, ordonnance, ordos, ordovician
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012