This adjective describes people lacking learning or instruction, being untaught or ignorant. In 2 Peter 3:16, unstable and 'ignorant' people twist Scripture to their destruction. Classical Greek used it for lack of education and, pejoratively, for stupidity or boorishness. The multilingual glosses (Spanish 'ignorantes', German 'ungelehrt') confirm this educational deficiency. Peter doesn't merely describe neutral lack of education but dangerous ignorance that, combined with instability, leads to misinterpreting difficult biblical texts with destructive consequences.