dimensionless (not comparable)

1. Lacking dimensions.

   Synonyms: adimensional

   • 1674, John Milton, “Book XI”, in Paradise Lost. A Poem in Twelve Books, 2nd revised and augmented edition, London: Printed by S[amuel] Simmons […], OCLC 563123917 ↗, page 286 ↗:

     To Heav'n thir prayers / Flew up, nor miſsd the way, by envious windes / Blow'n vagabond or fruſtrate: in they paſsd / Dimentionleſs through Heav'nly dores; [...]

   • 1771, William Kenrick (writer), A Lecture on Perpetual Motion, London, for the author, Introduction, p. 15,

     Extended objects may be separated by dimensionless points; but dimensionless points cannot be separated, but by some real distance, or something really extended.

   • 1930, E. E. Smith, Skylark Three, Fantasy Press, 1948, Chapter 3,

     They saw the utter, absolute darkness of the complete absence of all light; and upon that indescribable blackness they beheld superimposed the almost unbearable brilliance of enormous suns concentrated into mathematical points, dimensionless.

   • 1932, William Faulkner, chapter 10, in Light in August, [New York, N.Y.]: Harrison Smith & Robert Haas, OCLC 644581344 ↗; republished London: Chatto & Windus, 1933, OCLC 154633965 ↗, page 215 ↗:

     He did not look once again toward the dark house. [...] He simply went quietly as if that were his natural manner of moving and passed around the now dimensionless bulk of the house, toward the rear, where the kitchen would be.

2. (science) Of a physical constant: lacking units.

   Iron has a density of 7.8g/cc: its dimensionless relative density is 7.8.