Arcane and Impenetrable

Arcane

Arcane adjective - Difficult for one of ordinary knowledge or intelligence to understand.
Usage example: grammatical rules that seem arcane to generations of students who were never taught grammar in the first place

Impenetrable is a synonym for arcane in esoteric topic. In some cases you can use "Impenetrable" instead an adjective "Arcane", when it comes to topics like hidden.

Impenetrable

Impenetrable adjective - Being beyond one's powers to know, understand, or explain.
Usage example: the mysteries of that religion are completely impenetrable to outsiders

Arcane is a synonym for impenetrable in incomprehensible topic. You can use "Arcane" instead an adjective "Impenetrable".

Nearby Words: impenetrability, impenetrably
Cite this Source
Impenetrable and Arcane. (2016). Retrieved 2026, July 21, from https://thesaurus.plus/related/arcane/impenetrable
Arcane & Impenetrable. N.p., 2016. Web. 21 Jul. 2026. <https://thesaurus.plus/related/arcane/impenetrable>.
Impenetrable or Arcane. 2016. Accessed July 21, 2026. https://thesaurus.plus/related/arcane/impenetrable.
Google Ngram Viewer shows how "arcane" and "impenetrable" have occurred on timeline