Definition of "letterless"

I passed by a ruined tomb in the midst of a garden-way, Upon whose letterless stone seven blood-red anemones lay.

1880, John Payne, “Azizeh’s Tomb”, in New Poems‎, London: Newman & Co, page 98

The next morning’s post brought several letters; one from Roger for Cynthia, and Molly, letterless herself, looked at Cynthia as she read it, with wistful sadness.

1864 August – 1866 January, [Elizabeth] Gaskell, chapter 45, in Wives and Daughters. An Every-day Story. […], volumes (please specify |volume=I or II), London: Smith, Elder and Co., […], published 1866

There is not much more in this letter, and then we have unfortunately another gap of nearly two letterless years, there being none in my collection from June 6, 1811, until May 24, 1813.

1884, Edward, Lord Brabourne, “1811⁠”, in Jane Austen, edited by Edward, Lord Brabourne, Letters of Jane Austen, volume II, London: Richard Bentley & Son, […], page 82

The prospect of seeing some one who had just seen Tom was very exciting, but Nina’s happiness was dampened by the fact that just about that time she had three letterless days.

1914, Margaret Deland, chapter 5, in The Hands of Esau‎, New York: Harper & Bros., page 67

I knovv God by Miracle can inſtruct Kings, as he rained Mannah, and raiſed the Apoſtles from letterless Fiſher-men, to learned Metropolitans, and profound Doctours.

1663, Edward Waterhous [i.e., Edward Waterhouse], chapter I, in Fortescutus Illustratus; or A Commentary on that Nervous Treatise De Laudibus Legum Angliæ, Written by Sir John Fortescue Knight, […], London: […] Tho[mas] Roycroft for Thomas Dicas […], page 38

I join therefore in the public Assemblies, not because of the Purity, or Perfection of that which is done, or to be found there, but because of that which is meant and intended by them: They mean the holy, public Worship of God; they mean the Edification of Christians; they are of great Use to many People; they keep the World from a total Forgetfulness of God; they help the Ignorant and Letterless to such a Knowledge of God, and the Scriptures, as they would not have without them.

1760, William Law, A Collection of Letters, London: J. Richardson, Letter I, p. 20

The son of a small tobacconist, he had grown up a sign-painter’s apprentice; idle, lawless, and practically letterless until he had drifted into the night classes of the Albert League, where Ghillini sometimes lectured.

1905, Willa Cather, “The Marriage of Phaedra”, in The Troll Garden‎