recum+bent => sounds similar like become+bent. you become bent while sitting means you lie down.
recumbent -> re (phir) + cum (kamar means back) + bent. Apni kamar phir se bent karo means lie down.
Ray only cums when he's bent over or re-cum-bent. (Apologise for the graphical nature of this mnemonic, but I'm sure you'll agree that you'll remember it now!)
Can be derived from incumbent which means in office so one who is in office like a babu always lays back in the chair.
Sounds like recliner...one rests back in a recliner.