Of uncertain derivation; the jaw-bone, i.e. (by implication) the cheek or side of the face -- cheek.
Thayer's Greek Lexicon
Strong's 4600: σιαγών
σιαγών, σιαγόνος, ἡ, the jaw, the jaw-bone (A. V. cheek): Matthew 5:39; Luke 6:29. (Sophicles, Xenophon, Plato, Aristotle, others; the Sept. for לְחִי.)
Matthew 5:39 - N-AFS GRK:τὴν δεξιὰν σιαγόνα σου στρέψον NAS: you on your right cheek, turn KJV: thy right cheek, turn to him INT: the right cheek of you turn
Luke 6:29 - N-AFS GRK:ἐπὶ τὴν σιαγόνα πάρεχε καὶ NAS: Whoever hits you on the cheek, offer KJV: thee on the [one] cheek offer also INT: on the cheek offer also
