δυναμοδύναμις
From LSJ
ἔγνω δὲ φώρ τε φῶρα καὶ λύκος λύκον → the thief knows the thief and the wolf knows the wolf, and thief knows thief and wolf his fellow wolf, set a thief to catch a thief
English (LSJ)
εως, ἡ,
A square multiplied by square, fourth power, Hero Metr.1.17; fourth power of unknown quantity (x4), Dioph. Def.1 (pl.), al.: —hence δῠνᾰμο-δῠνᾰμοστόν, τό, the fraction 1/x4, Id.Def.3, al.