This noun denotes security, certainty, or safety. Luke writes his Gospel so Theophilus might know 'the certainty' of the things he was taught (Luke 1:4). The temple guard was found standing at their posts 'in all security,' though the prisoners had escaped (Acts 5:23). Paul warns that when people say 'peace and safety,' sudden destruction will come upon them (1 Thess 5:3). The word bridges intellectual certainty (firm knowledge) and physical security (protection from danger), both of which prove unreliable without divine foundation.