What does unsaturated mean?
“Unsaturated” is chiefly a technical adjective describing chemical compounds that do not contain the maximum possible number of hydrogen atoms. In organic chemistry, an unsaturated compound has at least one double or triple bond between carbon atoms, whereas a saturated compound has only single carbon–carbon bonds. The distinction is especially familiar in nutrition, where unsaturated fats and fatty acids are contrasted with saturated fats. Unsaturated fats are commonly associated with plant oils, nuts, seeds, and fish, although the term does not by itself indicate whether a fat is nutritionally desirable. More broadly, “unsaturated” can mean not filled or not completely engaged, but that use is relatively uncommon outside technical or formal contexts. The word is useful because it identifies a structural property with important consequences for chemical reactivity, physical properties, and biological function.
adjectiveNot saturated; especially, describing a chemical compound that contains one or more double or triple bonds between carbon atoms. In food and biology, it may describe fats or fatty acids that contain such bonds.
- Denoting a chemical compound or molecular structure that contains one or more double or triple bonds, especially between carbon atoms.
- Denoting a fat or fatty acid containing one or more such bonds; unsaturated fats are commonly associated with plant oils and are often distinguished from saturated fats.
- Used more generally to mean not saturated, not full, or not completely engaged.
"The recipe calls for olive oil, an unsaturated fat rich in monounsaturated fatty acids."
"Chemists classify the compound as unsaturated because its carbon chain contains a carbon–carbon double bond."
"The label lists unsaturated fatty acids as an alternative to the saturated fats traditionally found in this product."
In chemistry, the “un-” in unsaturated points to extra room in the molecular structure: unsaturated compounds have fewer hydrogen atoms and often behave quite differently from their saturated counterparts.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does unsaturated come from?
“Unsaturated” was formed in English by adding the prefix “un-” to “saturated.” “Saturated” comes through Latin from saturatus, the past participle of saturare, meaning “to fill” or “to saturate.” The same Latin root is reflected in English words such as “saturate,” “saturation,” “satiate,” and “satiety.”
How unsaturated is actually used
The technical meanings are most common in chemistry, nutrition, and biology. In general writing, “unsaturated” is less common than “not saturated” and may sound formal or specialized.
Easily confused with unsaturated
An unsaturated compound contains at least one double or triple bond between carbon atoms, whereas a saturated compound contains only single bonds and has the maximum number of hydrogen atoms.