occasion

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

• noun An event or happening, or the time of an event or happening.
• noun A significant event, especially a large or important social gathering.
• noun A favorable or appropriate time or juncture: synonym: opportunity.
• noun A cause of or reason for something: synonym: cause.
• noun A need created by a particular circumstance.
• noun Archaic Personal requirements or necessities.
• transitive verb To provide occasion for; cause.
• idiom (on occasion) From time to time; now and then.
• idiom (rise to the occasion) To find the ability to deal with an unexpected challenge.
• idiom (take the occasion) To make use of the opportunity (to do something).

from The Century Dictionary.

• noun An occurrence; an event; an incident; a happening.
• noun A special occurrence or happening; a particular time or season, especially one marked by some particular occurrence or juncture of circumstances; instance; time; season.
• noun An event which affords a person a reason or motive for doing something or seeking something to be done at a particular time, whether he desires it should be done or not; hence, an opportunity for bringing about a desired result; also, a need; an exigency.
• noun Used absolutely, though referring to a particular action.
• noun In negative phrases.
• noun In the abstract, convenience; opportunity: not referring to a particular act.
• noun Need; necessity: in the abstract.
• noun An accidental cause.
• noun An event, or series of events, which lead to a given result, but are not of such a nature as generally to produce such results: sometimes used loosely for an efficient cause in general, as in the example from Merlin.
• noun An incident cause, or cause determining the particular time when an event shall occur that is sure to be brought about sooner or later by other causes. The idea seems to be vague.
• noun Causal action; agency. See def. 4.
• noun Chance; occurrence; incident.
• noun A consideration; a reason for action, not necessarily an event that has just occurred.
• noun Business; affair: chiefly in the plural.
• noun A high event; a special ceremony or celebration; a function.
• noun plural Necessities of nature.
• noun Synonyms and Opportunity, Occasion. See opportunity.2, 3, and Occurrence, etc. (see exigency), conjuncture, necessity.
• To cause incidentally or indirectly; bring about or be the means of bringing about or producing; produce.
• To lead or induce by an occasion or opportunity; impel or induce by circumstances; impel; lead.
• Synonyms To bring about, give rise to, be the cause of.

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

• noun A falling out, happening, or coming to pass; hence, that which falls out or happens; occurrence; incident; event.
• noun A favorable opportunity; a convenient or timely chance; convenience.
• noun An occurrence or condition of affairs which brings with it some unlooked-for event; that which incidentally brings to pass an event, without being its efficient cause or sufficient reason; accidental or incidental cause.
• noun Need; exigency; requirement; necessity.
• noun A reason or excuse; a motive; a persuasion.
• noun occasionally; from time to time; now and then.
• transitive verb To give occasion to; to cause; to produce; to induce.

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

• verb transitive To give occasion to; to cause; to produce; to induce; as, to occasion anxiety.

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

• noun reason
• noun the time of a particular event
• verb give occasion to
• noun an opportunity to do something
• noun a vaguely specified social event
• noun an event that occurs at a critical time