If n is a whole number then we call it a perfect square if there is some whole m such that n = m^2.
If x is a rational number, then we call it a perfect square if there is some rational number w such that x = w^2. In fact if x=p/q is expressed in lowest terms (i.e. p and q have no common factor other than 1) and p >= 0, q > 0, then it is a perfect square if and only if both p and q are perfect squares.