google def: A rational number is a number that can be written as a ratio. That means it can be written as a fraction, in which both the numerator (the number on top) and the denominator (the number on the bottom) are whole numbers.
my def: A Rational Number is a real number that can be written as a simple fraction (i.e. as a ratio).
examples:
-1.5 is a rational number because 1.5 = 3/2 (it can be written as a fraction)
-5
-1.75
-.001