Толковый словарь английского языка Oxford English Reference - occasion

n. & v. --n. 1 a a special or noteworthy event or happening (dressed for the occasion). b the time or occurrence of this (on the occasion of their marriage). 2 (often foll. by for, or to + infin.) a reason, ground, or justification (there is no occasion to be angry). 3 a juncture suitable for doing something; an opportunity. 4 an immediate but subordinate or incidental cause (the assassination was the occasion of the war). --v.tr. 1 be the occasion or cause of; bring about esp. incidentally. 2 (foll. by to + infin.) cause (a person or thing to do something). Phrases and idioms on occasion now and then; when the need arises. rise to the occasion produce the necessary will, energy, ability, etc., in unusually demanding circumstances. take occasion (foll. by to + infin.) make use of the opportunity. Etymology: ME f. OF occasion or L occasio juncture, reason, f. occidere occas- go down (as OB-, cadere fall)