essential; fundamental; intrinsic
Describes the core, inherent nature of something, often used in formal or analytical contexts. 本質的な問題 (essential problem), 本質的に異なる (fundamentally different).
We need to investigate the essential cause of this problem.
The two opinions are fundamentally different.
These two problems are fundamentally different.
They investigated the underlying cause of the accident.
There is a fundamental problem with this system.