English Reference
noun

thinner

n.
US /ˈθɪnɝ/ UK /θˈɪnɐ/ thin·ner UK spelling thinners

  1. 01 B2 Upper Intermediate Cooking

    a liquid you add to paint or glue to make it thinner and easier to use.

    a volatile solvent used to reduce the viscosity of paints, varnishes, or adhesives for easier application.

    Simple

    You need to add some paint thinner to the brush before you start cleaning it.

    In context

    The artist carefully mixed a small amount of cellulose thinner into the oil paint to achieve the desired transparency for the base layer.

    Usage

    Often used in the compound 'paint thinner'.

    solventdiluent

The nanoparticles are around a thousand times thinner than a human hair.

Phys.org· 29 Aug 2026

It’s a few tenths of a millimeter thinner, but that’s not enough to notice unless you have both phones to compare.

Ars Technica· 19 Aug 2026

From thin + -er.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Level B2 · Upper Intermediate
Frequency Frequent
Updated