1. The chick on the side is that girl or woman that gives you what you're lacking at home or with your current significant other (main chick).
The chick on the side's duties may include but are not limited to: wild kinky sex, letting you vent out frustrations you may not want to with your main chick, keeping a low profile, understanding that she is not the main chick and can be dropped at any time with no explanation, being on call even if she hasn't heard from her lover in weeks or months.
2. A woman you have good times with, but have no serious commitment to.
3. A woman who will never have her lover's full respect, time or attention. In short someone who needs a good slaying and lies to herself in saying "I'm gettin' mine...", yeah right. You're confused girl.
also known as a "jump off"
My wifey left town for the weekend, so I'm about to hit up my chick on the side.