A transcendental

number is a number that cannot be expressed as a

root of a

polynomial equation with

rational coefficients. (Oppose

algebraic).

Some notable transcendental numbers:

Interestingly (to me, anyhow), although e

^{Pi} is known to be transcendental, it is not known whether or not e

^{e}, Pi

^{e}, or Pi

^{Pi} are transcendental.

Reference: Eric Weisstein's World of Mathematics

`http://mathworld.wolfram.com/TranscendentalNumber.html`