Entity
An entity is a thing that has a distinct, separate, reality.The general connotation of the word 'entity' is often of a being/creature/organism/lifeform with some kind of intelligence but not necessarily a concrete material existence; e.g. God is often referred to as an 'Entity' with no corporeal form.
However, the word 'entity' does not necessarily imply that the thing in question is intelligent, or living, and can be used of inanimate objects or non-material concepts. In this sense, the word is often just used as a synonym for "thing". For this reason, using the word 'entity' is useful when one wants to refer to what could either be a human being, a non-human animal, a non-thinking life-form such as a plant or fungus, or a lifeless object; for instance, one could say that any entity that enters a black hole would be transported, in many pieces, to another dimension.
In law, an entity is something capable of bearing legal rights and obligations -- legal entities generally include living persons and commercial entities.
Entity is the root node of the SUMO ontology, and stands for the universal class of individuals.
In VHDL, entity is the keyword for defining a new object.
An SGML entity is an abbreviation for some expanded piece of SGML text.