Englishfor English speakers
covariance
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noun
(statistics) the mean value of the product of the deviations of two variates from their respective means
contraction
Noun
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A contraction is when something pulls together and gets smaller. It is the act of contracting.
The cold weather made the bridge contract and break.
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A contraction is a word made of two other words, with letters and spaces removed, and an apostrophe added. It is different from a compound word, because a compound word doesn't have any letters removed. Most are informal.
In English class, we learned the contractions "don't" and "you're".