cotton wool

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Cotton in its natural or raw state.
• noun Chiefly British A cotton ball or a wad of cotton.

from The Century Dictionary.

• noun Raw cotton; cotton fiber either on the boll or prepared for use.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun US raw fibers of cotton before being processed
• noun UK absorbent cotton for medical or cosmetic use etc.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun soft silky fibers from cotton plants in their raw state