untempered

Untempered is an adjective meaning not tempered. In music theory, the term describes tuning systems that do not adjust intervals to fit a single equal-tempered octave. Untempered tunings use pure frequency ratios or alternative compromises, so that some intervals sound very consonant in some keys and very dissonant in others. Historically, most Western music before the widespread adoption of equal temperament relied on untempered tunings such as just intonation, Pythagorean tuning, or meantone temperament. Equal temperament, dominant from the late 18th century onward, divides the octave into equal semitones, enabling smooth modulation across keys. Untempered tunings preserve purity of intervals like the perfect fifth (3:2) or major third, but at the cost of keys with wolf intervals when tuned beyond certain ranges. In practice performers chose tuning systems to match instrument design and repertoire; keyboard instruments, for example, could expose wolf intervals in untempered systems.

In materials science and construction, untempered (or annealed) glass refers to glass that has not been heat-treated to improve strength. Untempered glass is more susceptible to impact breakage and shattering; tempered glass is heat-treated to increase toughness and safety. The term also appears in reference to metals or alloys that have not undergone tempering, a heat-treatment intended to adjust hardness and ductility.

The word derives from temper, meaning to condition, soften, or harden. In modern usage, untempered often contrasts with tempered or annealed forms, and with equal temperament in music theory.