vanishing point

vanishing point (plural vanishing points)

1. The point in a perspective drawing at which parallel lines receding from an observer seem to converge.
   • 1884, Wm. M. Thornton, “Construction of Perspective Projections”, in The Annals of Mathematics, volume 1, number 1, page 13:

     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.

2. The situation in which, place where, or point in time when some object or phenomenon is no longer observable or notable.
   • 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:

     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 seconds of time.

   • 1923 June 25, “Tuberculosis at Bay”, in Time:

     It might cut the tuberculosis deathrate to the vanishing point.

   • 2003 August 25, Sally B. Donnelly, “The Need for Speed”, in Time:

     It hit 100 m.p.h. with ease and sped toward the vanishing point down Highway 93A.

• point at infinity

• “vanishing point”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.
• “vanishing point”, in Merriam-Webster Online Dictionary, Springfield, Mass.: Merriam-Webster, 1996–present.