chief executive officer

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

• noun The highest-ranking executive in a company or organization.

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

• noun business The highest-ranking corporate officer or executive officer of a corporation, company, or agency, responsible for carrying out the policies of the board of directors on a day-to-day basis; CEO

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

• noun the corporate executive responsible for the operations of the firm; reports to a board of directors; may appoint other managers (including a president)