datum level or datum line
surveying the horizontal plane from which heights and depths are calculated
Why are planes named after numbers, like the 747? Is there a 947 or a 658?
After World War II, one of the largest aircraft manufacturers, Boeing, turned its attention from designing military craft to building commercial planes, along with missiles and spaceships. (Unrelated fact: when Boeing was forced to spin off its passenger flight division, the newly-formed company became United Airlines. Back to the late 1940s: Model numbers were assigned to each division of aircraft (from the Boeing website:) “300s …
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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
[dā′təm, dăt′əm, dä′təm]
An arbitrary plane used as a base from which to make craniometric measurements.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.