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# probability

[prob-uh-bil-i-tee] /ˌprɒb əˈbɪl ɪ ti/
noun, plural probabilities.
1.
the quality or fact of being probable.
2.
a strong likelihood or chance of something:
The probability of the book's success makes us optimistic.
3.
a probable event, circumstance, etc.:
Our going to China is a probability.
4.
Statistics.
1. the relative possibility that an event will occur, as expressed by the ratio of the number of actual occurrences to the total number of possible occurrences.
2. the relative frequency with which an event occurs or is likely to occur.
Idioms
5.
in all probability, very probably; quite likely:
The factory will in all probability be relocated.
Origin of probability
1545-1555
From the Latin word probābilitās, dating back to 1545-55. See probable, -ity
Related forms
nonprobability, noun, plural nonprobabilities.
superprobability, noun, plural superprobabilities.
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2017.
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Examples from the Web for probability
Contemporary Examples
• probability: 96 percent, unless this spring you finally gave up and ordered central air conditioning, in which case, 15 percent.

• A resurrection would be a miracle and as such would defy all “probability.”

• The best we can offer is a probability that an earthquake might occur along a fault in a given period of time.

• The meaning of a “probability” estimate can be understood by resorting to the last refuge of political metaphors: sports.

• In all probability, Americans will continue to be killed and wounded, but at a lower rate.

Historical Examples
• Let them ponder on the probability of succeeding with the people.

Charles Dickens
• Thus doubtless our hostess reasoned, and in all probability she was right.

Matilda Betham-Edwards
• Then there was some probability of being put in a coaster; which we might run away with.

James Fenimore Cooper
• The case is the same with the probability of causes, as with that of chance.

• So far the probability was against Arthur's being the author.

Mrs. Henry Wood
British Dictionary definitions for probability

## probability

/ˌprɒbəˈbɪlɪtɪ/
noun (pl) -ties
1.
the condition of being probable
2.
an event or other thing that is probable
3.
(statistics) a measure or estimate of the degree of confidence one may have in the occurrence of an event, measured on a scale from zero (impossibility) to one (certainty). It may be defined as the proportion of favourable outcomes to the total number of possibilities if these are indifferent (mathematical probability), or the proportion observed in a sample (empirical probability), or the limit of this as the sample size tends to infinity (relative frequency), or by more subjective criteria (subjective probability)
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for probability
n.

mid-15c., "quality of being probable," from Old French probabilite (14c.) and directly from Latin probabilitatem (nominative probabilitas) "credibility, probability," from probabilis (see probable). Meaning "something likely to be true" is from 1570s; mathematical sense is from 1718.

Online Etymology Dictionary, © 2010 Douglas Harper
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probability in Science
 probability   (prŏb'ə-bĭl'ĭ-tē)    A number expressing the likelihood of the occurrence of a given event, especially a fraction expressing how many times the event will happen in a given number of tests or experiments. For example, when rolling a six-sided die, the probability of rolling a particular side is 1 in 6, or 1/6 .
The American Heritage® Science Dictionary
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probability in Culture

### probability definition

A number between zero and one that shows how likely a certain event is. Usually, probability is expressed as a ratio: the number of experimental results that would produce the event divided by the number of experimental results considered possible. Thus, the probability of drawing the ten of clubs from an ordinary deck of cards is one in fifty-two (1:52), or one fifty-second.

The New Dictionary of Cultural Literacy, Third Edition
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Idioms and Phrases with probability

## probability

The American Heritage® Idioms Dictionary
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### Difficulty index for probability

Many English speakers likely know this word

### Word Value for probability

20
23
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