What does hydrophobicity mean?
Hydrophobicity is the property of a surface or material to repel water and resist becoming evenly wetted. Water tends to form rounded droplets on a strongly hydrophobic surface, as it does on waxed fabric or plant leaves, rather than spreading into a thin film. The term is common in chemistry, biology, materials science, and engineering, where researchers describe a surface as having high or low hydrophobicity and seek to increase it for products such as waterproof clothing, self-cleaning coatings, and outdoor sensors. Hydrophobicity should not be confused with hydrophilicity, which denotes a surface's attraction to water. Although the two properties are opposites, both can be useful: a hydrophobic coating can prevent unwanted wetting, while a hydrophilic surface can help water spread evenly for filtration, printing, or biological adhesion.
nounThe property of a surface or material to repel water and resist wetting. In chemistry and materials science, it describes the tendency of a substance to form water-repellent surfaces or droplets.
- The quality or degree of being hydrophobic, especially the ability of a material or surface to repel water.
"The coating's extreme hydrophobicity prevents water from clinging to the fabric."
"Wax gives paper some degree of hydrophobicity, allowing ink to bead on its surface."
"Engineers increased the film's hydrophobicity so that rain would roll off the solar panel."
The plural is uncommon; singular constructions such as "a high degree of hydrophobicity" are more usual in technical prose.
"The two coatings displayed markedly different hydrophobicities."
A self-cleaning raincoat works partly because droplets bead up on a hydrophobic surface instead of spreading into a flat film.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does hydrophobicity come from?
Hydrophobicity is a noun formed from the adjective hydrophobic, combining the English prefix hydro- with a form of the Greek-rooted term -phobic. The element hydro- comes from Greek hydōr, meaning water, while the broader -phob- element derives from Greek phobos, meaning fear. Related formations include hydrophilia, hydrophilicity, and hydrophobia, and the water-derived root also appears in hydrology and hydrous.
Related word forms
How hydrophobicity is actually used
The term is primarily used in chemistry, biology, materials science, and engineering. It normally appears with modifiers such as high, low, enhanced, or surface, and is more technical than the everyday phrase water repellency.
Easily confused with hydrophobicity
Hydrophobicity is the tendency to repel water, whereas hydrophilicity is the tendency to attract water and be readily wetted.
Hydrophobicity refers generally to water repellency, while oleophobicity specifically means resistance to oils and other nonpolar liquids.