A quarter is one fourth of something or twenty-five percent:
A quarter is one fourth of a dollar. It’s worth twenty-five cents. Four quarters make a dollar.
A fifteen-minute period of time is a quarter. The clock shows that it’s a quarter to six.
Sporting events such as American football may be divided into quarters: first quarter, second quarter, third quarter, and fourth quarter. Each quarter is fifteen minutes.
A quarter note in music is one fourth of a whole note.
Military quarters are places where soldiers live.
Closely related to the word "quarter" is the word "quart." This is often used when describing liquids:
A quart of milk is 32 ounces. It’s equivalent to two pints.
Two quarts make half a gallon or 64 ounces.
Four quarts make a gallon or 128 ounces.
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When people buy oil for their car, they often buy it by the quart. A quart of oil costs two or three dollars.
Businesses often talk about their yearly progress in terms of quarters. Each quarter is three months long:
The first quarter is January through March
The second quarter is April through June
The third quarter is July through September
The fourth quarter is October through December
Three quarters of the year have passed. We’re now in the fourth quarter.