The Greek adjective anoētos is a compound of an- (not) and noeō (to perceive, understand, think), meaning lacking spiritual or rational perception — foolish, senseless, or without understanding. It occurs 6 times in the New Testament and is used for both moral-spiritual failure and straightforward lack of comprehension.
Biblical foolishness is not primarily intellectual deficiency — it is moral-spiritual failure to perceive reality as God defines it. Anoētos appears in the Emmaus road encounter (Luke 24:25 — 'How foolish you are, and how slow to believe all that the prophets have spoken!') where Jesus gently rebukes the disciples' failure to connect Scripture to His resurrection. Galatians 3:1, 3 uses it more sharply: 'You foolish Galatians! Who has bewitched you?' — describing the spiritual regression of those turning from grace to law. Paul uses it in Titus 3:3 of the pre-conversion state. The corrective to anoētos is not more intelligence but the illumination of the Holy Spirit, who gives spiritual perception (1 Corinthians 2:12–14).