In music, well-tempered refers to a tuning system that slightly adjusts intervals so a keyboard instrument can sound acceptable in many keys. It does not mean “perfectly” pure tuning; it means carefully balanced tuning. In historical instrument making, the phrase points to precision, calibration, and an intentional trade-off between mathematical purity and practical use.
In cyber security, the term is not a standard technical control, but the idea is useful. Security teams often “temper” settings to balance protection and usability: cipher choices, password rules, rate limits, alert thresholds, and access policies all need careful tuning. If a system is over-tempered, it can become hard to use; if it is under-tempered, it may leave weak defaults, excessive permissions, or noisy monitoring that attackers can exploit. The phrase is therefore a good metaphor for defensive configuration, where small adjustments can strongly affect resilience.