untempered adj.

prefix of negation, Old English un-, from Proto-Germanic *un- (source also of Old Saxon, Old Frisian, Old High German, German un-, Gothic un-, Dutch on-), from PIE *n- (source of Sanskrit a-, an- "not," Greek a-, an-, Old Irish an-, Latin in-), combining form of PIE root *ne- "not." Often euphemistic (such as untruth for "lie").

The most prolific of English prefixes, freely and widely used in Old English, where it forms more than 1,000 compounds. It underwent a mass extinction in early Middle English, but emerged with renewed vigor 16c. to form compounds with native and imported words. It disputes with Latin-derived cognate in- (1) the right to form the negation of certain words (indigestable/undigestable, etc.), and though both might be deployed in cooperation to indicate shades of meaning (unfamous/infamous), typically they are not.

It also makes words from phrases (such as uncalled-for, c. 1600; undreamed-of, 1630s; uncome-at-able, 1690s; unputdownable, 1947, of a book; un-in-one-breath-utterable, Ben Jonson; etc., but the habit is not restricted to un-; such as put-up-able-with, 1812). As a prefix in telegramese to replace not and save the cost of a word, it is attested by 1936.

late Old English temprian "to moderate, bring to a proper or suitable state, to modify some excessive quality, to restrain within due limits," from Latin temperare "observe proper measure, be moderate, restrain oneself," also transitive, "mix correctly, mix in due proportion; regulate, rule, govern, manage." This is often described as from Latin tempus "time, season" (see temporal), with a sense of "proper time or season." But as the root sense of tempus seems to be "stretch," the words in the "restrain, modify" sense might be from a semantic shift from "stretching" to "measuring" (compare temple (n.1)). Meaning "to make (steel) hard and elastic" is from late 14c. Sense of "tune the pitch of a musical instrument" is recorded from c. 1300. Related: Tempered; tempering.