triangulation

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A surveying technique in which a region is divided into a series of triangular elements based on a line of known length so that accurate measurements of distances and directions may be made by the application of trigonometry.
• noun The network of triangles so laid out.
• noun The location of an unknown point, as in navigation, by the formation of a triangle having the unknown point and two known points as the vertices.
• noun The establishment of a political position that differs from two existing or opposing positions, especially in being moderate.

from The Century Dictionary.

• noun A making triangular; formation into triangles.
• noun The operation and immediate result of measuring (ordinarily with a theodolite) the angles of a network of triangles laid out on the earth's surface by marking their vertices.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Surv.) The series or network of triangles into which the face of a country, or any portion of it, is divided in a trigonometrical survey; the operation of measuring the elements necessary to determine the triangles into which the country to be surveyed is supposed to be divided, and thus to fix the positions and distances of the several points connected by them.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun uncountable A technique in surveying in which distances and directions are estimated from an accurately measured baseline and the principles of trigonometry
• noun countable The network of triangles, so obtained, that are the basis of a map or chart
• noun uncountable In navigation or seismology, a process by which an unknown location is found using three known distances from known locations.
• noun chess A delaying move in which the king moves in a triangular path in order to force the advance of a pawn.
• noun qualitative research The use of three (or more) researchers to interview the same people or to evaluate the same evidence to reduce the impact of individual bias.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a method of surveying; the area is divided into triangles and the length of one side and its angles with the other two are measured, then the lengths of the other sides can be calculated
• noun a trigonometric method of determining the position of a fixed point from the angles to it from two fixed points a known distance apart; useful in navigation