What does deliquescence mean?
Deliquescence refers to the process by which certain water-soluble solids — most often salts such as calcium chloride, potassium hydroxide, or ferric ammonium citrate — absorb so much moisture from the surrounding air that they dissolve in it, forming a saturated aqueous solution. A substance that behaves this way is described as hygroscopic or, more precisely, deliquescent, and each has a characteristic relative humidity at which the process begins, known as its deliquescence point. This property matters practically: deliquescent chemicals must be stored in airtight containers, and their moisture-drawing ability makes them useful as drying agents. The word also appears occasionally in a figurative, literary sense to describe something gradually melting away or losing definition. Though largely confined to scientific writing, deliquescence is a vivid and precise term for a phenomenon most people have witnessed without knowing its name — a spilled salt crystal slowly turning damp and syrupy on a humid day.
The tendency of a soluble substance to absorb moisture from the atmosphere until it dissolves in the absorbed water and forms a solution.
"The deliquescence of anhydrous copper sulfate exposed it to contamination from the laboratory air."
Chiefly technical; the related adjective 'deliquescent' is more frequent in everyday scientific prose.
A melting away, dissolving, or gradual disintegration, used figuratively.
"Critics noted the novel's deliquescence of plot into pure sensation."
Rare and literary.
Almost always used as an uncountable mass noun; plural forms occur only rarely, typically when referring to multiple distinct instances or types of the phenomenon.
"The paper compared the deliquescences of several common fertilizers under varying humidity conditions."
Leave a tub of calcium chloride open on a muggy day and it will literally drink the air around it, dissolving into its own captured water — that's deliquescence.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of deliquescence
Deliquescence derives from the Latin verb 'deliquescere', meaning 'to melt away' or 'to dissolve', formed from the intensive prefix 'de-' plus 'liquescere', itself from 'liquēre' ('to be fluid'). English adopted the term in the late eighteenth century as chemists sought precise language for the behavior of hygroscopic salts. It belongs to a large family of English words built on the same Latin root 'liquēre', including 'liquid', 'liquefy', and 'liquor'.
Related word forms
How deliquescence is actually used
Predominantly a technical term used in chemistry, materials science, and meteorology; figurative uses are rare and literary. The adjective form 'deliquescent' is more commonly encountered than the noun.
Easily confused with deliquescence
Effervescence is the bubbling release of gas from a liquid, whereas deliquescence is the absorption of airborne moisture until a solid dissolves into solution.
Liquefaction is any conversion of a solid or gas into liquid form, while deliquescence specifically means a solid drawing water vapor from the surrounding air and dissolving in it.