What does "scour" mean?

Additional senses

1. 2.To remove by rubbing or cleansing; to sweep along or off; to carry away or remove, as by a current of water; -- often with off or away. [I will] stain my favors in a bloody mask, Which, washed away, shall scour my shame with it. Shak.
2. 3.Etym: [Perhaps a different word; cf. OF. escorre, escourre, It. scorrere, both fr. L. excurrere to run forth. Cf. Excursion.] To pass swiftly over; to brush along; to traverse or search thoroughly; as, to scour the coast. Not so when swift Camilla scours the plain. Pope. Scouring barrel, a tumbling barrel. See under Tumbling. -- Scouring cinder (Metal.), a basic slag, which attacks the lining of a shaft furnace. Raymond. -- Scouring rush. (Bot.) See Dutch rush, under Dutch. -- Scouring stock (Woolen Manuf.), a kind of fulling mill.
3. 4.To clean anything by rubbing. Shak.
4. 5.To cleanse anything. Warm water is softer than cold, for it scoureth better. Bacon.
5. 6.To be purged freely; to have a diarrhoea.
6. 7.To run swiftly; to rove or range in pursuit or search of something; to scamper. So four fierce coursers, starting to the race, Scour through the plain, and lengthen every pace. Dryden.
7. 8.Diarrhoea or dysentery among cattle.