This noun denotes exactness, precision, strict accuracy, or rigorous adherence to standards. Classical usage applied it to careful precision, minute detail, and strict discipline. Paul uses it in Acts 22:3 describing his training: "brought up in this city, educated at the feet of Gamaliel according to the strictness of the ancestral law." The term emphasizes the rigorous, precise nature of Paul's Pharisaic education—not casual familiarity with Torah but exacting study of every detail, strict observance of interpretive tradition, precise application of legal minutiae. This careful training made Paul a zealous Pharisee before becoming an apostle.