Key
Key adjective - Coming before all others in importance.
Usage example: maintains that Sir Isaac Newton remains the key figure in physical science
Primary is a synonym for key in fundamental topic. In some cases you can use "Primary" instead the word "Key" as an adjective or a noun, when it comes to topics like property, principal, main, important. popular alternative
Primary
Primary adjective - Coming before all others in importance.
Usage example: the primary concern for many house hunters is the asking price
Key is a synonym for primary in main topic. You can use "Key" instead the word "Primary" as an adjective or a noun, if it concerns topics such as major, property, principal, important. popular alternative
Mutual synonyms
Both words in one sentence
- While Jon himself wasn't too important, as the primary rebel spy character his death robbed the rebels of a key information source, forced another character to go underground, and eventually caused a mandatory execution which itself was a huge source of drama.
Source: Roleplay / Equestria Chronicles -
Jack Bruce was the bassist and primary singer of Cream, and has had an low-key but well-regarded solo career.
Source: Lead Bassist - Save the Princess: She becomes a key figure in the plots of those who want to turn the country towards their own ends and one of the prince's primary motivations for fighting.
Source: Characters / Suikoden V
Cite this Source
Primary and Key. (2016). Retrieved 2026, August 16, from https://thesaurus.plus/related/key/primary
Key & Primary. N.p., 2016. Web. 16 Aug. 2026. <https://thesaurus.plus/related/key/primary>.
Primary or Key. 2016. Accessed August 16, 2026. https://thesaurus.plus/related/key/primary.
Google Ngram Viewer shows how "key" and "primary" have occurred on timeline