Extended Strong's Greek Lexicon (Abbott-Smith based)
foolish
Usage: μωρός, -ά, -όν [in LXX for נָבָל, etc.; frequently in Sir. ;] __1. prop., of the nerves, dull, sluggish (Hipp., Arist.). __2. Of the mind, dull, stupid, foolish: Mat.5:22 (see Field, Notes, 3 ff.) Mat.7:26 23:17, 19 (T, WH, txt., R, om.) Mat.25:2-3, 8, 1Co.3:18 4:10; of things, παράδοσις, Mrk.7:13 (T, WH, txt., R, om.) : ζητήσεις, 2Ti.2:23, Tit.3:9; τὸ μ. τ. θεοῦ, 1Co.1:25; τὰ μ. τ. κόσμου, 1Co.1:27.† (AS)