everything

Everything is a term used to denote the totality of what exists or is considered within a given framework. In ordinary language, it refers to all things within a specified domain, such as the visible world, a conversation, or a particular system of thought.

In philosophy and logic, "everything" raises questions about the nature of totality and self-reference. The idea of a set that contains all sets leads to paradoxes; most formal theories of mathematics, such as ZFC, do not include a universal set. Instead, "everything" is modeled relative to a universe or model. In cosmology, discussions distinguish the observable universe from the entire Universe, and some theories posit more than one universe (multiverse).

In science, "everything" often means all physical entities and phenomena described by current theories, within the limits of measurement and observation. The boundary of everything can be the cosmological horizon; beyond is speculative and not empirically accessible. The concept is also used in informal contexts to indicate completeness within a framework, or a totalizing claim, which is often qualified by scope or time.

In linguistics and everyday language, "everything" functions as a determiner or pronoun with scope determined by context. It can be negated ("not everything"), restricted by a phrase ("everything but"), or focused ("everything in this room").

Overall, "everything" is a flexible, context-dependent notion that serves as a practical shorthand for the totality within a reference frame, and its exact meaning depends on the domain being discussed.