English edit

 
A half-round file.
 
Three flat files (from left to right: smooth, second cut, bastard). The bastard file is coarser than the other two depicted, but not as coarse as a rough file.

Noun edit

bastard file (plural bastard files)

  1. A half-round file or rasp (being a flat file on one side, and a round file on the other); typically having coarse teeth.
  2. A file of intermediate cut, neither very coarse nor very fine.

See also edit

  • adj. bastard in the sense of "hybrid" or "impure".