Short light sleep (3)
(Other definitions for nap that I've seen before include "soft, fluffy surface" , "A brief informal sleep" , "Quick sleep; raised pile" , "Kip" , "A short sleep or snooze" .)
(Other definitions for catnap that I've seen before include "little snooze" , "Drop off" , "Brief time out" , "Brief doze" , "(Tom's) snooze?" .)