Eldest
Eldest adjective - First in order of birth.
Firm and eldest are semantically related. in traditional topic. In some cases you can use "Firm" instead an adjective "Eldest".
Cite this Source
Firm and Eldest. (2016). Retrieved 2026, July 29, from https://thesaurus.plus/related/eldest/firm
Eldest & Firm. N.p., 2016. Web. 29 Jul. 2026. <https://thesaurus.plus/related/eldest/firm>.
Firm or Eldest. 2016. Accessed July 29, 2026. https://thesaurus.plus/related/eldest/firm.
Google Ngram Viewer shows how "eldest" and "firm" have occurred on timeline