the length of time something continues or exists (often used with the ).

continuance in time.

(in the philosophy of Bergson) a temporal continuum, intuitively known, within which the élan vital operates.

noun

continuance , continuation , continuity , endurance , extent , period , perpetuation , persistence , prolongation , run , span , spell , stretch , term , tide , time , continuum , persistency , day , existence , lifetime , infinitude , infinity , length , longanimity , longevity , perpetuality , perpetuity , perseverance