How do you spell Pebble

Available Definitions:
1)  n. - A small roundish stone or bowlder; especially, a stone worn and rounded by the action of water; a pebblestone.
2)  n. - Transparent and colorless rock crystal; as, Brazilian pebble; -- so called by opticians.
3)  v. t. - To grain (leather) so as to produce a surface covered with small rounded prominences.