An approximation is a result close enough for a practical purpose, though it is not exact. It may come from rounding, estimation, measurement, or a method designed to produce a near-value. Slide rules, for example, use aligned scales to estimate calculations rather than return calculator-level precision.
In cyber security, approximation can help analysts make quick estimates when exact data is unavailable or unnecessary-for example, judging likely risk or prioritizing alerts. It also matters when interpreting security tools: estimates, thresholds, and probabilistic detections should not be mistaken for certainty. Approximate results can guide decisions, but high-impact actions may require verification against more precise evidence.