Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio.
a surveying device for plotting maps in the field: it consists of a drawing board mounted on a tripod with an alidade that can be moved about over the table to establish a reference point
Used by arrangement with John Wiley & Sons, Inc.
nounThe American Heritage® Dictionary of the English Language, 4th edition Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
A portable surveying instrument consisting essentially of a drawing board and a ruler mounted on a tripod and used to sight and map topographical details.