You can use retention to mean the ability to keep or hold. If you have extraordinary powers of retention, you remember everything you hear or learn.
Are your ankles ever swollen after a long flight? This comes from the lack of movement which can cause the retention of water. The roots of the word, Latin re- "back" and tenere "to hold," say it all. You often use the word in the military or business contexts to talk about keeping soldiers, or employees, from leaving. If you're lucky, they might offer you a retention bonus to prevent you from quitting.