"grit from a grinding tool," 1560s, perhaps ultimately from Old English geswearf "filings," from sweorfan, or from a Scandinavian source akin to Old Norse svarf "file dust," related to sverfa "to file," from PIE *swerbh- "to turn, wipe off" (see swerve, v.). Later used of the material cut out to make grooves of gramophone records (1935).