essencial

Essencial is a Portuguese adjective meaning essential, fundamental, or indispensable. It is used to describe elements, features, or requirements that are necessary to the core function, identity, or integrity of a person, object, system, or concept. The word often conveys priority or central importance, as opposed to auxiliary or optional parts.

Etymology and usage: The term derives from Latin essentia, through French essential/essentiel, and into Portuguese. The related noun essência denotes the essence or nature of a thing. The distinction between essencial and non-essencial mirrors the broader distinction between essential and nonessential in many disciplines.

In philosophy, essentialism posits that certain properties are essential to a thing's identity. An essential property is one that the object must have to be what it is; properties that are not essential may vary without changing the object's fundamental nature.

In science and health, essencial is used for things the body cannot synthesize in sufficient amounts and must obtain from the diet. This includes essential nutrients such as essential amino acids (nine in adults) and essential fatty acids like linoleic and alpha-linolenic acids. The term also appears in policy and industry to label indispensable services, components, or information.

See also: essentialism; essential amino acid; essential fatty acid.