vanishing points

Noun

vanishing point (plural vanishing points)

1. The point in a perspective drawing at which parallel lines receding from an observer seem to converge.
   • These formulae . . . give for the vanishing point of a set of parallel lines whose common azimuth is α and declivity δ: η=d tan α, ζ=d tan δ sec α.1884, Wm. M. Thornton, “Construction of Perspective Projections”, in The Annals of Mathematics, volume 1, number 1, page 13
2. The situation in which, place where, or point in time when some object or phenomenon is no longer observable or notable.
   • At 8h 35' 4", the least dent possible, quite black, appeared in the sun's limb. And at 8h 35' 6", the limb was restored to its perfect form, there having been a small trembling light, between the narrow watery border of Venus and the vanishing point of contact in the sun's limb for these two...1762, Samuel Dunn, “Some Observations of the Planet Venus, on the Disk of the Sun, June 6th, 1761,”, in Philosophical Transactions (1683-1775), volume 52, page 192