noun
Refers to the central, essential, or most important part of something, similar to English 'core'. Used in both concrete and abstract contexts.
この問題のコアは何ですか。
What is the core of this problem?
地球のコアは非常に高温だ。
The Earth's core is extremely hot.
na-adjective
Colloquial adjectival use describing something as extreme, intense, or deeply committed, often in the context of hobbies, fandoms, or subcultures.
彼はコアなゲーマーだ。
He is a hardcore gamer.
このバンドはコアなファンに支えられている。
This band is supported by passionate fans.