What is the term for the time required for the capacitor in an RC circuit to be charged to 63.2% of the applied voltage or to discharge to 36.8% of its initial voltage?

Explication

Charging and discharging in an RC circuit follow an exponential curve whose characteristic interval is the product of resistance and capacitance. After that one interval the capacitor has reached 63.2% of the applied voltage when charging, or fallen to 36.8% of its starting voltage when discharging.