끈질겨요 · 끈질겼어요 · 끈질긴 (+noun)
persistent, tenacious, relentless
Example
그 기자는 대답을 들을 때까지 끈질기게 질문했어요.
The reporter kept asking persistently until he got an answer.
Word parts
Probably related to 끈기 'stickiness' + 질기다 'tough, chewy' — hard to break.
Good to know
Can be positive (tenacious) or negative (relentless), depending on context.
Related words