성실해요 · 성실했어요 · 성실한 (+noun)
sincere, conscientious, diligent
Example
그 학생은 성실해서 숙제를 항상 해 와요.
That student is conscientious, so they always do their homework.
Word parts
성 sincere+실 true
Literally 'sincere and true' — someone you can count on.
Related words