commencement

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

• noun A beginning; a start.
• noun A ceremony at which academic degrees or diplomas are conferred.
• noun The day on which such a ceremony occurs.

from The Century Dictionary.

• noun The act or fact of commencing; beginning; rise; origin; first existence; inception.
• noun In the University of Cambridge, England, the day when masters of arts, doctors, and bachelors receive their degrees: so called from the fact that the candidate commences master, doctor, licentiate, etc., on that day. See commence, v. i., 3.
• noun In American colleges, the annual ceremonies with which the members of the graduating class are made bachelors (of arts, sciences, engineering, etc.), and the degree of master of arts and various honorary degrees are conferred.

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

• noun The first existence of anything; act or fact of commencing; rise; origin; beginning; start.
• noun The day when degrees are conferred by colleges and universities upon students and others.

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

• noun The first existence of anything; act or fact of commencing; rise; origin; beginning; start.
• noun The day when degrees are conferred by colleges and universities upon students and others.
• noun A graduation ceremony, from a school, college or university.

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

• noun the time at which something is supposed to begin
• noun the act of starting something
• noun an academic exercise in which diplomas are conferred