The Greek verb agnoeō (ἀγνοέω) means to not know, to be ignorant, to fail to understand — from the privative a- (not) and noeō (to perceive/understand). It describes both culpable ignorance (willful refusal to know) and non-culpable ignorance (genuine lack of knowledge). The related noun agnoēma (G51) means a sin of ignorance, and agnoia (G52) means ignorance or a state of not knowing. The Septuagint uses it to translate Hebrew terms for unintentional sin (Numbers 15:24–29).
Ignorance in Scripture is complex: sometimes it diminishes guilt (Acts 17:30 — God "overlooked" the times of ignorance before Christ; Luke 23:34 — "they do not know what they are doing"), and sometimes it is itself sinful (Romans 10:3 — Israel's ignorance of God's righteousness was a willful refusal). Paul uses agnoeō repeatedly to introduce important theological teaching — "Brothers and sisters, I do not want you to be ignorant..." (Romans 1:13; 11:25; 1 Corinthians 10:1) — implying that ignorance of key doctrines has real consequences. The opposite of agnoeō is ginōskō (to know) — the deep, relational, experiential knowledge of God that comes through Christ (John 17:3). The call to move from ignorance to knowledge is the call to discipleship and repentance.