A reference point on high ground used in surveying, typically marked by a small pillar.Bear left on the top to join the tarmac of the mast access road and the trig point summit pillar is passed on the left....
A bank and ditch ran north-west towards the main camp on the central knoll near the trig point.
When I eventually reached the trig point on the 2,759 ft / 841m summit of Vrackie I swore I would never climb the hill again.
Origin
Mid 19th century: abbreviation of trigonometrical point.