σφηνοειδής
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
English (LSJ)
ές,
A wedge-shaped, Thphr.CP1.6.8, Ascl.Tact.7.2, Heliod. ap. Orib.49.4.35, Gal.2.752.