Key
Key adjective - Coming before all others in importance.
Usage example: maintains that Sir Isaac Newton remains the key figure in physical science
Principal is a synonym for key in essential topic. In some cases you can use "Principal" instead the word "Key" as an adjective or a noun, when it comes to topics like main, important, major, chief. popular alternative
Principal
Principal adjective - Coming before all others in importance.
Usage example: our principal reason for coming here today
Key is a synonym for principal in main topic. You can use "Key" instead the word "Principal" as an adjective or a noun, if it concerns topics such as important, major, chief, fundamental. popular alternative
Mutual synonyms
How words are described
Both words in one sentence
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In RS2, Phil enters the principal's office, takes the key to the front door, and bolts... all directly in front of the principal, who just stands there the whole time.
Source: Video Game / Riddle School -
Ferris looks for the key, but his Genre Savvy principal has already taken it.
Source: Key Under the Doormat - In RS3, the principal is too busy playing video games to notice as Phil swipes the key.
Source: Video Game / Riddle School
Cite this Source
Principal and Key. (2016). Retrieved 2026, July 21, from https://thesaurus.plus/related/key/principal
Key & Principal. N.p., 2016. Web. 21 Jul. 2026. <https://thesaurus.plus/related/key/principal>.
Principal or Key. 2016. Accessed July 21, 2026. https://thesaurus.plus/related/key/principal.
Google Ngram Viewer shows how "key" and "principal" have occurred on timeline