Deep
Deep adjective - Extending far downward.
Usage example: the ax made a deep cut into the wood
Unfathomable is a synonym for deep in profound topic. In some cases you can use "Unfathomable" instead the word "Deep" as an adjective or a noun, when it comes to topics like big, bottomless, fathomless, obscure. popular alternative
Unfathomable
Unfathomable adjective - Impossible to understand.
Usage example: for some unfathomable reason the family decided to venture out into the blizzard
Deep is a synonym for unfathomable in bottomless topic. You can use "Deep" instead the word "Unfathomable" as an adjective or a noun, if it concerns topics such as fathomless, inscrutable, hard to believe. popular alternative
Mutual synonyms
Related pairs
- complex and deep
- complex and unfathomable
- heavy and deep
- heavy and unfathomable
- profound and deep
- profound and unfathomable
- bottomless and deep
- bottomless and unfathomable
- abstruse and deep
- abstruse and unfathomable
- abysmal and deep
- abysmal and unfathomable
- fathomless and deep
- fathomless and unfathomable
Both words in one sentence
- Much is made of his androgynous good looks, and he tends to come off a bit deep and unfathomable when he's having a prescient moment.
Source: Literature / Weathercock - Lexie plans to keep her baby, but also plans to sell her share of the house to do so - a betrayal so deep and unfathomable that it drives Justin to stab her in his fury and confusion.
Source: Literature / The Likeness -
Waltz, to an unfathomable degree, if his recollections and impossibly deep regret are any indication.
Source: Fan Fic / Yet again
Cite this Source
Unfathomable and Deep. (2016). Retrieved 2026, July 21, from https://thesaurus.plus/related/deep/unfathomable
Deep & Unfathomable. N.p., 2016. Web. 21 Jul. 2026. <https://thesaurus.plus/related/deep/unfathomable>.
Unfathomable or Deep. 2016. Accessed July 21, 2026. https://thesaurus.plus/related/deep/unfathomable.
Google Ngram Viewer shows how "deep" and "unfathomable" have occurred on timeline