εἰκοῦς

From LSJ

ὃν οὐ τύπτει λόγος οὐδὲ ῥάβδος → if words don't get through, neither a beating will | if the carrot doesn't work, the stick will not work either | whom words do not strike, neither does the rod

Source

French (Bailly abrégé)

gén. sg. contr. de εἰκών.

Russian (Dvoretsky)

εἰκοῦς: Eur. стяж. gen. к εἰκών.