σκληρ-ύνω,
harden, opposed to μαλάσσω, [[ 5th c.BC: Hippocrates Medicus “περὶ διαίτης ὀξέων” 45, 4th c.BC: Aristoteles Philosophus “Historia Animalium” 548b23 ] Refs 5th c.BC+]:—passive, with perfect ἐσκλήρυσμαι [[ 5th c.BC: Hippocrates Medicus “περὶ ὑγρῶν χρήσιος” 6, and -υμμαι] Refs 5th c.BC+], to be hardened, grow hard, [[ [prev. author] “VM” 22, 4th-3rd c.BC: Theophrastus Philosophus “de Lapidibus” 11. ] Refs 4th c.BC+]
__2 metaphorically, σ. τὴν καρδίαν τινός harden his heart, [[ LXX.Exo.7.3, +others, NT.Heb.3.8,cf. NT.Rom.9.18 ] LXX+NT]:—passive, [[ LXX.Sir.30.12. ] LXX]