Ratio is a word derived from Latin. It is used in this sense in several languages, including French and English. Depending on the context, it may have the following meanings;

In mathematics, a ratio between two numbers is the first report by the second. For example, "the ratio of x on y" equals.
In finance, a financial ratio is a ratio between two accounts of the balance sheet or income statement.
In law, the ratio decidendi is the legal reasoning that led a judge to decide. He opposes the obiter dictum.
In computing, printing, digital, painting, photography, video, the phrase is the aspect ratio format of a digital image or paper or a sheet which the ratio of the width by the height remains the same.
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