First-class
First-class adjective - Of the very best kind.
Key and first-class are semantically related. In some cases you can use "Key" instead an adjective phrase "First-class".
Key
Key adjective - Coming before all others in importance.
First-class and key are semantically related. Sometimes you can use "First-class" instead an adjective "Key".
Mutual synonyms
Cite this Source
Key and First-class. (2016). Retrieved 2026, July 22, from https://thesaurus.plus/related/first-class/key
First-class & Key. N.p., 2016. Web. 22 Jul. 2026. <https://thesaurus.plus/related/first-class/key>.
Key or First-class. 2016. Accessed July 22, 2026. https://thesaurus.plus/related/first-class/key.
