Emily Dickinson Lexicon

COB'BLE, or COB'BLE-STONE, n. [Eng. copple. This seems to be of Welch origin, W. cub, a mass, a cube, or cob, cop, head, top.]

A roundish stone; a pebble; supposed to be a fragment, rounded by the attrition of water. We give this name to stones of various sizes, from that of a hen's egg or smaller, to that of large paving stones. These stones are called by the English copple-stones, and bowlder-stones, or bowlders. The latter name is among us known only in books.