From Longman Dictionary of Contemporary Englishnail fileˈnail file noun [countable] DCBa thin piece of metal with a rough surface used for making your nails a nice shape
Examples from the Corpus
nail file• Peg opens a drawer and gets out a nail file from a manicure set.• He glanced around, then took a nail file from his pocket and set to work on the padlock.• If they're a bit blunt rub the tip with a nail file.• Contains: two pairs of angled scissors, tweezers, large and small angled cuticle pushers, nail file and cleaner.• I had to bend over, parallel to the body, to get the nail file under the nails. 