0 a point at the top of a hill or mountain, usually marked by a small stone or concrete structure, used in surveying (= measuring and recording details of the distances, heights, etc. of areas of land):
We sat with our backs against the trig point and gazed down like gods on the coastal plain of Thassos.
The other, less steep, ridge leads directly to the summit cairn and trig point at 3,442ft/1,049m.
He was so taken in by the view that he stepped back from the trig point and disappeared over the edge of the crag that crowns the top.
