Abbott-Smith Manual Greek Lexicon
ἄφρων (G878)
11 ἄφρων , -ον gen. -ονος ( φρήν ), [in LXX for כְּסִיל , נָבָל , etc.;] without reason , senseless , foolish , expressing "want of mental sanity and sobriety, a reckless and inconsiderate habit of mind" (Hort; cf. MM, s.v.): Lk 11:40 12:20 , Ro 2:20 , I Co 15:36 , II Co 11:16 12:6 , 11 , I Pe 2:15 ; opp. to φρόνιμος , II Co 11:19 ; to συνιέντες , Eph 2:17 .†
G. Abbott-Smith, A Manual Greek Lexicon of the New Testament (1922) — public domain