undiluted

Undiluted is an adjective describing a substance that has not been mixed with another substance to reduce its concentration. In common usage, it refers to a solution, mixture, or liquid that remains in its original, concentrated form rather than being diluted with a solvent such as water or another liquid.

In chemistry and pharmacology, dilution lowers the amount of solute per unit of solvent, changing properties like concentration, potency, and vapor pressure. The term undiluted contrasts with diluted solutions measured by molarity, percent by volume, or dilution factor. A dilution increases volume while maintaining the same amount of solute, whereas undiluted implies the initial, concentrated state before any dilution.

Practical contexts vary. In beverage service, undiluted typically means served neat, without ice or water. In cosmetics and essential oils, undiluted or “neat” products contain the ingredient at full strength. Cleaning products, disinfectants, and some agrochemicals may be labeled undiluted to indicate they should not be mixed with water before use, as mixing can cause hazards such as irritation or chemical reactions.

Safety and regulatory notes: undiluted substances can pose greater risks of burns, toxicity, or corrosion. Manufacturers may specify storage, handling, and disposal requirements. In laboratory practice, clear labeling helps ensure correct dilution for experiments and safety.

Other uses: the term can be used metaphorically to describe something as pure or unaltered, for example “undiluted enthusiasm” or “undiluted truth.” Etymology: from the idea of not having been diluted, related to the Latin diluere and the noun dilution; related terms include diluted.