I've read this:
In mathematics, a transcendental number is a (possibly complex) number that is not algebraic—that is, it is not a root of a non-zero polynomial equation with rational coefficients.
Why does the concept of transcendental numbers was appended to polynomials with rational coefficients? Why not polynomials with real or complex coefficients? By the few mathematical readings I have done, I felt that it's not safe to work with reals or complex numbers in some mathematical concepts, I speculate that this safety (in the case of the transcendental numbers) can only be granted with rational numbers.