Merriam-Webster Collegiate Dictionary - opening

 noun  Date: 13th century  1.  a. an act or instance of making or becoming open  b. an act or instance of beginning ; commencement; especially a formal and usually public event by which something new is put officially into operation  2. something that is open: as  a.  (1) breach, aperture  (2) an open width ; span  b. an area without trees or with scattered usually mature trees that occurs as a break in a forest  c. two pages that face one another in a book  3. something that constitutes a beginning: as  a. a usually planned series of moves made at the beginning of a game of chess or checkers — compare endgame, middle game  b. a first performance  4.  a. occasion, chance  b. an opportunity for employment