key signature

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

• noun The group of sharps or flats placed to the right of the clef on a staff to identify the key.

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

• noun music An indication of the key of a composition, giving the number of sharps or flats in the corresponding scale.

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

• noun the sharps or flats that follow the clef and indicate the key