A measurement number that determines how long it takes for a battery to be completely discharged or charged.
A discharge rate of 1C stands for a 1-hour discharge, 2C for 1/2-hour discharge, 10C for 6-minute discharge, etc. The discharge rate is independent of the capacity of a battery.
Analogue, 1C also stands for 1 hour charge, 2C for 1/2 hour charge etc. Here, this is the time required to fully charge the battery.