unscathed (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 12c., scathen, "to harm, injure, hurt; to cause harm, damage, or loss to," from Old Norse skaða "to hurt, harm, damage, injure," from Proto-Germanic *skathan- (source also of Old English sceaþian "to hurt, injure," Old Saxon skathon, Old Frisian skathia, Middle Dutch scaden, Dutch schaden, Old High German scadon, German schaden, Gothic scaþjan "to injure, damage").

In some sources this is traced to a PIE *sket- "to injure." The Germanic word was seen as cognate with some Celtic formations and Greek a-skēthēs "unharmed, unscathed," but Beekes finds that connection "impossible" on phonetic grounds and Boutkan, agreeing, writes that "The etymon is limited to Celt.-Gmc." and offers no IE etymology.

It survives mostly in its negative past participle unscathed, and in the figurative meaning "sear with invective or satire" (1852, usually as scathing). The latter seems to have developed specifically from the word in the sense of "scar, scorch" used by Milton in "Paradise Lost" (1667).