What does hygroscopicity mean?
Hygroscopicity is the property of a substance to attract and absorb water vapour from the air. The term is especially useful when comparing materials by how strongly they respond to atmospheric moisture: a highly hygroscopic material can draw enough moisture from humid air to become damp, swell, dissolve, or deteriorate. Hygroscopicity is relevant in fields including chemistry, pharmaceuticals, construction, food packaging, and textile science. It helps explain why substances such as salt, sugar, silica gel, and many common paper products absorb moisture under humid conditions. The word is more specific than simply describing something as “wet”: hygroscopicity identifies a tendency to take in moisture from the surrounding atmosphere. In technical writing, it is often used quantitatively, allowing the moisture-absorbing behaviour of different materials to be measured and compared.
nounThe property of a material or substance of absorbing moisture from the surrounding air. It also refers to the degree to which a material exhibits this property.
- The tendency or degree of a material to absorb moisture from its surroundings.
"The coating was applied to reduce the hygroscopicity of the paper and protect it from dampness."
"High hygroscopicity can cause building materials to swell or deteriorate in humid conditions."
"The researchers compared the hygroscopicity of several natural fibres before selecting one for the filters."
The plural is grammatically possible but rarely needed because the term is usually used for an individual material or measured property.
"The study compared the hygroscopicities of the two powdered ingredients."
Silica-gel packets owe their usefulness to hygroscopicity: they eagerly pull moisture out of the air.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does hygroscopicity come from?
Hygroscopicity was formed from hygroscopic with the suffix -ity, meaning “the condition or quality of being.” Hygroscopic in turn comes through New Latin from Greek roots associated with hygros, “moist,” and skopein, “to observe or examine.” Related English terms include hygrometer, an instrument for measuring humidity, and hygrometry, the measurement of atmospheric moisture.
Related word forms
How hygroscopicity is actually used
A technical term used chiefly in chemistry, materials science, pharmaceuticals, and related fields. It describes a material's capacity to absorb atmospheric moisture, whereas hygroscopy may refer more broadly to the study or measurement of humidity.