noun
Abstract noun referring to the state or quality of being complex. Often used in technical or formal contexts.
この問題の複雑性を理解するのは難しい。
It is difficult to understand the complexity of this problem.
noun-modifying (irregular)
Prenominal use, often in medical or technical contexts, describing something as complex or complicated. Not a standalone adjective.
複雑性骨折の治療には時間がかかる。
Treatment for a complex fracture takes time.