concert pitch

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

• noun The state of being ready and tensely alert.

from The Century Dictionary.

• noun In music, the pitch used in tuning instruments for concert use. See pitch.

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

• noun music the pitch that is heard (usually with a transposed instrument)

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

• noun the pitch used to tune instruments for concert performances; usually assigns 440 Hz to the A above middle C