Occasion, n.
Etymology: [F. occasion, L. occasio, fr.occidere, occasum, to fall down; ob (see Ob-) + cadere to fall. See Chance, and cf. Occident.]
1. A falling out, happening, or coming to pass; hence, that which falls out or happens; occurrence; incident. The unlooked-for incidents of family history, and its hidden excitements, and its arduous occasions. I. Taylor.
2. A favorable opportunity; a convenient or timely chance; convenience. Sin, taking occasion by the commandment, deceived me. Rom. vii. 11. I'll take the occasion which he gives to bring Him to his death. Waller.
3. 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. Her beauty was the occasion of the war. Dryden.
4. Need; exigency; requirement; necessity; as, I have no occasion for firearms. After we have served ourselves and our own occasions. Jer. Taylor. When my occasions took me into France. Burke.
2 more senses
5. A reason or excuse; a motive; a persuasion. Whose manner was, all passengers to stay, And entertain with her occasions sly. Spenser. On occasion, in case of need; in necessity; as convenience requires; occasionally. "That we might have intelligence from him on occasion," De Foe.
Syn. -- Need; incident; use. See Opportunity.
1 other Webster entry under this spelling
Occasion, v. t. [imp. & p. p. Occasioned; p. pr. & vb. n. Occasioning.]
To give occasion to; to cause; to produce; to induce; as, to occasion anxiety. South. If we inquire what it is that occasions men to make several combinations of simple ideas into distinct modes. Locke.
Shades of meaning
Fernald has no entry of its own for occasion; he lists it under cause, make.
Where he writes about it:
An occasion is some event which brings a cause into action at a particular moment; gravitation and heat are the causes of an avalanche; the steep incline of the mountain-side is a necessary condition, and the shout of the traveler may be the occasion of its fall. — from cause
Extemporaneous, originally signifying of or from the time or occasion, has come to mean done or made with but little (if any) preparation, and is now chiefly applied to addresses of which the thought has been prepared, and only the language and incidental treatment left to the suggestion of the moment, so that an extemporaneous speech is understood to be any one that is not read or recited; impromptu keeps its original sense, denoting something that springs from the instant; the impromptu utterance is generally brief, direct, and vigorous; the extemporaneous speech may chance to be prosy. — from extemporaneous