썸네일이 · 썸네일을
thumbnail (preview image)
Example
썸네일이 재미있어 보여서 영상을 눌러 봤어요.
The thumbnail looked fun, so I clicked on the video.
Word parts
From English 'thumbnail'.
Good to know
The official spelling is 섬네일 (English th is written ㅅ), but 썸네일 is what almost everyone writes and says.
Related words