What does thinner mean?
Thinner is the comparative form of thin and means having less thickness, width, bulk, or density than something else. It can describe a person as more slender, an object as less bulky, or a substance as more fluid or concentrated. For example, air becomes thinner at high altitude, while a painter may add solvent to make thick paint thinner. The word is also established as a noun: a paint thinner is a liquid used to dilute paint and clean suitable brushes, and "the thinner" can name the more slender or less bulky member of a pair. Although thinner suggests a comparison, it does not always require an explicit second item; its intended standard is commonly understood from context. The term is standard in both British and American English across everyday, technical, and commercial contexts.
The comparative of thin: having less thickness, width, density, or physical bulk than something else; more slender, less concentrated, or more fluid.
"The mixture needs to be thinner before it can be poured."
Thinner is the standard comparative form in both British and American English.
A person or thing that is comparatively thin or slender; especially, a solvent used to dilute paint, varnish, or a similar substance.
"Use a paint thinner to clean the brush."
The count plural thinners applies to substances or agents; constructions such as "the thinner of the two" are normally singular and are not pluralized.
Used when referring to multiple people or things that are thin, or multiple solvents or agents used for thinning.
"Paint thinners should be stored in a well-ventilated place."
The same comparison can describe both a wafer-thin sheet and a soup loosened with water: both can become thinner.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does thinner come from?
Thinner was formed from thin by adding the comparative suffix -er. Thin descends from Old English þynne, meaning slender or lacking thickness or density, and ultimately from Proto-Germanic *þunnuz. Cognates from the same Germanic root include German dünn, Dutch dun, Danish tynd, and Icelandic þunnur.
Related word forms
How thinner is actually used
As an adjective, thinner is the standard comparative of thin and is widely used in formal and informal British and American English. It can describe reduced physical thickness, reduced density, or a more fluid consistency. As a noun, it most commonly refers to a solvent used to dilute paint, while phrases such as "the thinner of the two" use it as a nominal comparative.