1) In general, a ratio is a way of concisely showing the relationship between two quantities of something. The most formal way of stating a ratio is by separating the two quantities with a colon (:) although sometimes a division sign (/) is used in place of the colon. Thus, where there is a ratio of 5:2 between apples and oranges, for each five apples, there are two oranges.
For a ratio to have meaning, both numbers must be nonzero.
2) In mathematics, a ratio is a quotient used to compare quantities of the same units of measure.