expectation

From Middle French expectation, from Latin exspectātiō, from exspectō (“expect”); synchronically analyzable as expect +‎ -ation.

• (UK, US) IPA^(key): /ɛkspɛkˈteɪʃən/

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• Rhymes: -eɪʃən

expectation (countable and uncountable, plural expectations)

1. The act or state of expecting or looking forward to an event as about to happen.
   • 1907, Robert William Chambers, chapter IX, in The Younger Set, New York, N.Y.: D. Appleton & Company, OCLC 24962326:

     “A tight little craft,” was Austin’s invariable comment on the matron; […]. ¶ Near her wandered her husband, orientally bland, invariably affable, and from time to time squinting sideways, as usual, in the ever-renewed expectation that he might catch a glimpse of his stiff, retroussé moustache.

2. That which is expected or looked for.
   • 1922, Michael Arlen, “Ep./1/1”, in “Piracy”: A Romantic Chronicle of These Days:

     And so it had always pleased M. Stutz to expect great things from the dark young man whom he had first seen in his early twenties ; and his expectations had waxed rather than waned on hearing the faint bruit of the love of Ivor and Virginia—for Virginia, M. Stutz thought, would bring fineness to a point in a man like Ivor Marlay, […].

3. The prospect of the future; grounds upon which something excellent is expected to occur; prospect of anything good to come, especially of property or rank.
   • 1816, Jane Austen, Emma, Vol.1 Ch.7:

     Emma was not sorry to be pressed. She read, and was surprized. The style of the letter was much above her expectation. There were not merely no grammatical errors, but as a composition it would not have disgraced a gentleman; the language, though plain, was strong and unaffected, and the sentiments it conveyed very much to the credit of the writer. It was short, but expressed good sense, warm attachment, liberality, propriety, even delicacy of feeling. She paused over it, while Harriet stood anxiously watching for her opinion, with a "Well, well," and was at last forced to add, "Is it a good letter? or is it too short?"

4. The value of any chance (as the prospect of prize or property) which depends upon some contingent event.
5. (statistics) The first moment; the long-run average value of a variable over many independent repetitions of an experiment.
6. (colloquial statistics) The arithmetic mean.
7. (medicine, rare) The leaving of a disease principally to the efforts of nature to effect a cure.

• (value of any chance): Expectations are computed for or against the occurrence of the event.

• (colloquial statistics, arithmetic mean): arithmetic mean; average

• expect
• expectant
• expected

• (statistics): Wikipedia:Expected value