length, duration - continuance in time; "the ceremony was of short duration"; "he complained about the length of time required"

perpetuity, sempiternity - the property of being perpetual (seemingly ceaseless)

durability, enduringness, lastingness, strength - permanence by virtue of the power to resist stress or force; "they advertised the durability of their products"

imperishability, imperishingness - the property of being resistant to decay; "he advertised the imperishability of the product"

perdurability - the property of being extremely durable

immortality - the quality or state of being immortal