The Oxford Thesaurus An A-Z Dictionary of Synonyms - occasionn.

1) time, moment, circumstance, incident, occurrence, opportunity, chance, opening, advantage: I took the occasion of the inquiry to leave town. 2) reason, cause, call, justification, ground(s) , warrant, provocation, prompting, impulse, stimulus, incitement, inducement: Tom gave David no occasion to doubt his honesty. 3) event, function, happening, affair, observance, commemoration, ceremony, celebration, gala, party,: Grandpapa's ninetieth birthday was a great occasion. This hall is saved for important occasions. 4) on occasion. See occasionally, below. --v. 5) give rise to, bring about, cause, bring on, effect, prompt, provoke, evoke, call forth, elicit, call up, induce, impel, create, generate, engender, produce, make (for) : An increase in the inflation rate occasions a decrease in the value of money.