noun
A tool used for smoothing or shaping metal, wood, etc. The word is usually written in kana.
金属のバリをやすりで削る。
I file down the burrs on the metal with a file.
木工には目の粗いやすりが便利だ。
A coarse file is handy for woodworking.
The origin is uncertain. The kanji 鑢 is a kokuji (Japanese-made character) combining 金 (metal) and 慮, but the word itself is likely a native Japanese term.