Greek τὸ πᾶν (to pan), "the all"; Latin summa rerum (Lucretius)
The totality of everything that exists. The universe as a whole is infinite in size and eternal: nothing exists outside it that could enter it or change it. See The Universe Is Infinite In Size And Eternal In Time.
1. Key Texts
Quote from Epicurus, Letter to Herodotus 39 (The Totality Is Eternal and Unchanging)Moreover, the totality of things was always such as it is now, and always will be, since there is nothing into which it changes, and since beside the totality there is nothing which could pass into it and produce the change. (tr. Long & Sedley)