rubber band

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

• noun An elastic loop of natural or synthetic rubber used to hold objects together.

from the GNU version of the Collaborative International Dictionary of English.

• noun A closed loop of rubber usually having a thin rectangular cross-section; also called elastic band; -- it varies in length from the circumference of a finger to several inches, and is usually used to hold several objects together temporarily, by the tension exerted when the band is stretched and fitted around the objects to be held.

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

• noun An elastic band made of rubber.

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

• noun a narrow band of elastic rubber used to hold things (such as papers) together