Fluid
Firm
Firm adjective - Having been established and usually not subject to change.
Usage example: the selling price of the house is firm, so there'll be no dickering
Cite this Source
Firm and Fluid. (2016). Retrieved 2026, August 09, from https://thesaurus.plus/related/fluid/firm
Fluid & Firm. N.p., 2016. Web. 09 Aug. 2026. <https://thesaurus.plus/related/fluid/firm>.
Firm or Fluid. 2016. Accessed August 09, 2026. https://thesaurus.plus/related/fluid/firm.
Google Ngram Viewer shows how "fluid" and "firm" have occurred on timeline