WordNet records no synonym and no antonym for triangulation. It is the only member of each of its synsets, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
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
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
Synonyms, antonyms and the broader and narrower relations for triangulation come from Princeton University’s WordNet. Full sources and licences.