FROM STRONG’S GREEK DICTIONARY (1890)

Strong’s Greek Dictionary (1890) — public domain, printed whole.

aphron ἄφρων — af'-rone — from 1 (as a negative particle) and 5424; properly, mindless, i.e. stupid, (by implication) ignorant, (specially) egotistic, (practically) rash, or (morally) unbelieving:--fool(-ish), unwise.

see GREEK for 1

see GREEK for 5424