Abbott-Smith Manual Greek Lexicon
πλάξ (G4109)
3 πλάξ , -ακός, ἡ , [in LXX for לוּחַ ;] anything flat and broad . a plain (poët.). In late writers (Luc., al.), a flat stone , a tablet : II Co 3:3 , He 9:4 .†
G. Abbott-Smith, A Manual Greek Lexicon of the New Testament (1922) — public domain