(noun) - "Hue" is what we call any color that can be plucked, in a pure state, out of the light spectrum. Think of a rainbow, or that array of colors one gets when using a prism - the results are hues. It all has to do with light and wavelengths thereof.
Confusion creeps in to this definition when speaking of hues of pigmented color, rather than elements of the light spectrum. In this context (pigmented color), the phrase "a hue of blue/red/yellow/insert color here" is often bandied about, when the more accurate terms shade or tint should be employed.