Pebble

Part of speech: noun (n.)

1. A small roundish stone or bowlder; especially, a stone worn and rounded by the action of water; a pebblestone. "The pebbles on the hungry beach." Shak. As children gathering pebbles on the shore. Milton.

2. Transparent and colorless rock crystal; as, Brazilian pebble; -- so called by opticians. Pebble powder, slow-burning gunpowder, in large cubical grains. -- Scotch pebble, varieties of quartz, as agate, chalcedony, etc., obtained from cavities in amygdaloid.

Part of speech: verb (v.)

To grain (leather) so as to produce a surface covered with small rounded prominences.