Fixed
Fixed adjective - Having been established and usually not subject to change.
Usage example: the baseball card dealer's prices were fixed, so bargaining was not an option
Flat is a synonym for fixed in manner topic. In some cases you can use "Flat" instead an adjective "Fixed", when it comes to topics like change.
Cite this Source
Flat and Fixed. (2016). Retrieved 2026, August 14, from https://thesaurus.plus/related/fixed/flat
Fixed & Flat. N.p., 2016. Web. 14 Aug. 2026. <https://thesaurus.plus/related/fixed/flat>.
Flat or Fixed. 2016. Accessed August 14, 2026. https://thesaurus.plus/related/fixed/flat.
Google Ngram Viewer shows how "fixed" and "flat" have occurred on timeline