What does nonaqueous mean?
Nonaqueous is a technical adjective used chiefly in chemistry for a substance, solution, solvent, or medium that does not have water as its principal component. In a nonaqueous solvent, another liquid dissolves or carries the substances involved, allowing chemical processes to occur without the bulk of the solvent being water. The term is especially important in electrochemistry, pharmaceuticals, paints, coatings, and laboratory analysis, where water may react with a reagent, dissolve an undesired material, or interfere with a reaction. Nonaqueous does not always mean absolutely water-free: a mixture may be classified as nonaqueous even if it contains traces of moisture. Its principal opposite is aqueous, meaning water-based. The term is more precise than the informal phrase “water-free” in contexts where even a small amount of water matters.
adjectiveNot containing water or not having water as the solvent. In chemistry, the term describes a solution, solvent, or medium in which water is not the principal liquid.
- Not containing water, especially not having water as the principal solvent or medium in a chemical system.
"The coating was dissolved in a nonaqueous solvent to protect it from moisture."
"The battery uses a nonaqueous electrolyte that is less volatile than water."
"Nonaqueous cleaning solutions can remove grease without leaving a water-based residue."
Aqueous means water-based; nonaqueous means the water has left the main act.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does nonaqueous come from?
Nonaqueous was formed in English by combining the Latin-derived prefix non-, meaning “not,” with aqueous, an adjective derived from Latin aqua, “water.” The same Latin root produced words such as aquatic, aquarium, and aqueduct, while aqueous retained its direct sense of pertaining to or containing water.
Related word forms
How nonaqueous is actually used
Chiefly used in chemistry and materials science. It is not always a strict synonym for anhydrous, because a nominally nonaqueous system may contain small quantities of water.
Easily confused with nonaqueous
Anhydrous means completely free of water, whereas nonaqueous means that water is not the principal solvent or medium and may still be present in small amounts.