emery board

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A nail file consisting of a strip of cardboard coated with powdered emery.

Century Dictionary and Cyclopedia

1. n. Cardboardpulp mixed with emery-dust and cast in cakes.

Wiktionary

1. n. An abrasive material made by gluing grains of emery a rigid material. Often used as a nail file.

GNU Webster's 1913

1. n. cardboard pulp mixed with emery and molded into convenient.