A ratio's an expression that compares quantities relative to each other. The most common examples involve two quantities, but any number of quantities can be compared. Ratios are represented mathematically by separating each quantity with a colon, for example the ratio 2:3, which's read as the ratio "two to three". The quantities separated by colons are sometimes called terms. Etymology The word ratio comes from the Latin word of the same name. Examples The quantities being compared in a ratio… (More on Ratio)