conventional
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 > Greek (Woodhouse)
adjective
customary: P. and V. συνήθης, νόμιμος.
does this theory please you better, that names are merely conventional symbols: P. ἢ ὅδε μᾶλλον ἀρέσκει ὁ τρόπος… τὸ συνθήματα εἶναι τὰ ὀνόματα (Plato, orat. 433E).