Definition of "coping"

Three chairs of the steamer type, all maimed, comprised the furniture of this roof-garden, with (by way of local colour) on one of the copings a row of four red clay flower-pots filled with sun-baked dust […].

1914, Louis Joseph Vance, chapter I, in Nobody, New York, N.Y.: George H[enry] Doran Company, published 1915

He stood a moment at the coping, looking over a land of hard little bungalows with abnormally large porches, and new apartment-houses, small, but brave with variegated brick walls and terra-cotta trimmings.

1922, Sinclair Lewis, “28”, in Babbitt