μαχαίριον
From LSJ
ἐν πέτροισι πέτρον ἐκτρίβων → by grinding stone against stones
English (LSJ)
τό, = foreg., X.An.4.7.16, Men.765, PEleph.5.13 (iii B. C.), Str.12.2.10;
A surgeon's or barber's knife, Hp.Medic.6,7, Arist. GA789b13, Metaph.1061a4, Com.Adesp.327, Plu.Brut.13, Ruf.Ren. Ves.12.12.