Volume
Definition
The perceived loudness of a sound. In a mix context, volume refers to the fader level controlling the output of a channel after all processing has been applied.
In Simple Terms
How loud something sounds to your ears. In a mix, it's the fader position — the most basic and most important control you have. Great mixing is mostly just setting the right volumes for each element.
In Practice
After processing, a vocal fader is pulled back slightly to sit within the dense arrangement of the chorus without competing with the guitars.