Deep
Deep adjective - Extreme in degree, power, or effect.
Usage example: fell into a deep sleep after taking the potion
Keen is a synonym for deep in wise topic. In some cases you can use "Keen" instead the word "Deep" as an adjective or a noun, when it comes to topics like earnest, discerning, scheming.
Keen
Keen adjective - Extreme in degree, power, or effect.
Usage example: movies gave him keen enjoyment like nothing else
Mutual synonyms
Both words in one sentence
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Marr must have had tremendous patience: and a keen sense of how much to feed his songwriting partner's ultimately-doomed (aren't they always?) infatuations, without getting in too deep.
Source: Ho Yay / Music - In Season 11, while Chima was never too keen on following rules, after Jeff used the coup d'etat to overthrow her nominations she went off the deep end.
Source: Series / Big Brother -
Proud Warrior Race: The Vy'keen are a warrior sentient species with a reciprocal honor system (doing something for one obligates the Vy'Keen to do something for the doer and vice-versa), and a deep veneration of their ancient ancestors.
Source: Video Game / No Man's Sky
Cite this Source
Keen and Deep. (2016). Retrieved 2026, August 16, from https://thesaurus.plus/related/deep/keen
Deep & Keen. N.p., 2016. Web. 16 Aug. 2026. <https://thesaurus.plus/related/deep/keen>.
Keen or Deep. 2016. Accessed August 16, 2026. https://thesaurus.plus/related/deep/keen.
Google Ngram Viewer shows how "deep" and "keen" have occurred on timeline