Definition of "discrete"

There are two laws discrete, / Not reconciled,— / Law for man, and law for thing; / The last builds town and fleet, / But it runs wild, / And doth the man unking.

a. 1856, Ralph Waldo Emerson, “Ode, Inscribed to W. H. Channing”, in Poems, 5th edition, Boston: Pillips, Sampson & Co., published 1856, page 120

But analysis, penetrating beneath the fact of Sense in search of its ideal factors, declares that this mass of marble is something very different from what it appears : its seeming continuity is broken up into discrete molecules, separated from each other as the stars in the Milky Way are separated ; and its seeming homogeneity is resolved into heterogeneous substances, which are themselves in all probability composite.

1875, George Henry Lewes, “The Problem Stated”, in Problems of Life and Mind, volume II, London: Trübner & Co., page 33

It's not that there aren't measurable, quantifiable differences between all these categories we impose upon things, it's just that for the most part they fit not into discrete units, but into a continuum.

2017, Adam Rutherford, A Brief History of Everyone Who Ever Lived, The Experiment, pages 254–255