WordNet records no synonym and no antonym for triangulate. 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.
divide into triangles or give a triangular form to
“triangulate the piece of cardboard”
measure by using trigonometry
“triangulate the angle”
survey by triangulation
“The land surveyor worked by triangulating the plot”
1 of the 4 recorded senses carries no synonym, antonym or related term, so it is not shown above. Every sense, with its definition and examples, is on the full entry for triangulate.
Synonyms, antonyms and the broader and narrower relations for triangulate come from Princeton University’s WordNet. Full sources and licences.