pure

Pure is an adjective used to describe something that is free from contamination, dilution, or modification, and is often associated with sameness of composition or authenticity. In everyday language it can refer to substances with a definite, uniform composition (for example, pure water or pure gold) or to things considered unmixed or unaltered.

In science, a pure substance is one that has a single chemical composition and consistent properties throughout, as opposed to a mixture. Pure substances include elements and chemical compounds. They have characteristic melting and boiling points and cannot be separated into other substances by physical means alone; if separation is possible, it typically involves chemical change or more advanced techniques after purification. Purification methods such as distillation, crystallization, and chromatography are used to increase purity in laboratory and industrial contexts.

In mathematics and computer science, the term pure appears in several related ideas. A pure function is one that has no side effects and returns the same result given the same inputs. In a broader sense, pure mathematics refers to studying abstract structures without immediate concern for practical applications, as opposed to applied mathematics.

In cultural usage, pure can be part of branding or descriptive phrases, implying cleanliness, simplicity, or authenticity. The word is often adopted by companies for products and services to convey quality or unadulterated characteristics. The meaning of pure thus varies with context, spanning science, philosophy, mathematics, and everyday language.