They mean "fraction" as in "part", the same way that an arm is a fraction of a whole body. But it's more about the words we use in everyday language than about

They mean "fraction" as in "part", the same way that an arm is a fraction of a whole body. But it's more about the words we use in everyday language than about mathematical definitions. Also, I think I remember that the definition of a rational number implies fractions of integers. Otherwise I could write π as π/1 and give you a rational representation of π.