expectation
Pluralexpectations
- 1Whatever someone expects or looks for in a given situation.
The job fell short of his expectation of steady, meaningful work.
Reality rarely matches the expectations we build up beforehand.
Similarhope, assumption, anticipation, belief, prediction
Note
Here the word shifts from the waiting to the thing waited for. It is usually plural and measures results: trains that have "not come up to expectations" (Trains Illustrated, 1961). Expectations can also rise or fall, as when Michael Arlen's M. Stutz finds his "waxed rather than waned." Fall short of, meet and exceed belong to the same family of phrases.
- 2Anticipation of an event that one believes will soon take place, or the act of awaiting it.
She opened the letter with breathless expectation.
Months of expectation ended the moment the train finally arrived.
Similaranticipation, expectancy, suspense, eagerness
Note
The root sense, built on Latin exspectātiō, from exspectō, "expect." It came through Middle French and displaced the native Old English wēn. It names a state of mind, so it works with or without an article and often takes a that-clause. Robert W. Chambers's The Younger Set (1907) has a husband squinting sideways "in the ever-renewed expectation that" something will happen.
- 3An unstated obligation or duty that one person believes another is bound to fulfill.
The role carried an expectation of constant availability that no contract mentioned.
Cultural expectations often shape how children treat their aging parents.
Similarobligation, requirement, demand, duty, assumption
Note
A narrowing of the thing looked for: what one person looks for becomes what another feels bound to deliver. The possessive names who holds the expectation, and the duty falls on someone else. In "his parents' expectations," the parents expect and the son struggles. The plural is usual, and the obligation is unspoken by definition.
- 4The prospect of good things to come, especially the likelihood of inheriting property or gaining rank.
With no expectation of land or title, he set out to make his own way.
The family's expectations rested entirely on a distant relative's will.
Similarprospect, hope, outlook
Note
A word from the world of inheritance, at home in nineteenth-century fiction. A suitor who "had expectations" stood to come into money or rank. Letitia Elizabeth Landon (1838) calls the term "so vague when those expectations depend upon others," because the fortune hung on someone else's will or death. Used absolutely in the plural, with no object, it still carries that sense of property to come.
- 5The long-run average value of a variable over many independent repetitions of an experiment.
Engineers computed the expectation of the signal to predict its average strength.
For a fair coin scored one or zero, the expectation equals one half.
Note
A statistician's term, interchangeable with "expected value" and with "first moment." The last name places it at the head of a family of quantities that describe a variable's distribution. It belongs to a variable and its possibilities, not to any particular set of observations. You speak of the expectation of a random variable, and repeated trials only approach it.
- 6The value of a chance (such as the prospect of a prize or property) that depends on some uncertain future event.
An insurer prices each policy by estimating the expectation attached to an uncertain loss.
The heir's expectation depended wholly on whether the childless lord died without a will.
Similarexpectancy, prospect
Note
Here the hope gets a price. A legacy or prize that may never arrive is given a present worth according to the uncertain event it depends on. This turns prospects of property into something that can be valued. It also stands close to the statistician's expected value, which applies the same idea of a probability-weighted value to a variable.
- 7The arithmetic mean of a set of values.
She reported the expectation of the daily temperatures across the month.
The analyst quoted the expectation of the sample rather than its median.
Note
A looser, everyday use within statistics, where the word simply stands for the average of a set of numbers. Careful writers keep it apart from the expected value. That one is a property of a variable in theory, while the arithmetic mean is computed from data actually collected. In formal work, "mean" or "sample mean" avoids the ambiguity.
Less common meaning
- 8The practice of leaving a disease largely to the healing efforts of nature rather than active treatment.
The physician chose expectation over bleeding the patient, trusting nature to mend the fever.
Treatment then leaned heavily on expectation, with rest and time doing most of the work.
Note
A rare medical use that keeps the old idea of waiting inside the word. The physician stands back and expects nature to do the curing. It is easy to misread as hope or prediction. In a medical text, "treatment by expectation" means a deliberate choice to hold back from active intervention.
Practice
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Origin
This word came through Middle French "expectation" from Latin "exspectātiō," based on "exspectō" ("expect"); by surface analysis it is "expect" plus "-ation." It displaced the native Old English "wēn."