na-adjective
nontrivial; non-obvious
Technical term used in mathematics, logic, and formal contexts to describe a solution, proof, or fact that is not immediately apparent or requires significant reasoning.
この定理の証明は非自明な補題に依存している。
The proof of this theorem relies on a nontrivial lemma.
一見簡単そうに見えるが、実は非自明な問題だ。
It looks simple at first glance, but it is actually a non-obvious problem.