occasion vs opening

occasion

noun
  • A favorable opportunity; a convenient or timely chance. 

  • Need; requirement, necessity. 

  • The time when something happens. 

  • Something which causes something else; a cause. 

  • A reason or excuse; a motive; a persuasion. 

  • A special event or function. 

  • A particular happening; an instance or time when something occurred. 

  • An occurrence or state of affairs which causes some event or reaction; a motive or reason. 

verb
  • To cause; to produce; to induce 

opening

noun
  • An opportunity, as in a competitive activity. 

  • The first few measures of a musical composition. 

  • The first performance of a show or play by a particular troupe. 

  • A gap permitting passage through. 

  • The initial period when a show at an art gallery or museum is first opened, especially the first evening. 

  • A vacant position, especially in an array. 

  • An unoccupied employment position. 

  • In mathematical morphology, the dilation of the erosion of a set. 

  • An act or instance of making or becoming open. 

  • A time available in a schedule. 

  • An act or instance of beginning. 

  • The first few moves in a game. 

adj
  • Pertaining to the start or beginning of a series of events. 

  • describing the first period of play, usually up to the fall of the first wicket; describing a batsman who opens the innings or a bowler who opens the attack 

How often have the words occasion and opening occurred in a corpus of books? (source: Google Ngram Viewer )