n. 1 a small smooth stone worn by the action of water. 2 a a type of colourless transparent rock-crystal used for spectacles. b a lens of this. c (attrib.) colloq. (of a spectacle-lens) very thick and convex. 3 an agate or other gem, esp. when found as a pebble in a stream etc. not the only pebble on the beach (esp. of a person) easily replaced. pebble-dash mortar with pebbles in it used as a coating for external walls. pebbly adj.
[ OE papel-stan pebble-stone, pyppelripig pebble-stream, of unkn. orig. ]