unreconstructed 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.

1768, "build anew, build again," from re- "back, again" + construct (v.). Meaning "to restore (something) mentally, construct anew in the mind again" is attested from 1862. Related: Reconstructed; reconstructing.

1791, "action or process of reconstructing," noun of action to go with reconstruct. In U.S. history, usually with a capital R-, it has been used from 1865 in reference to the process (lasting until about 1870) by which the states which had seceded were restored to the rights and privileges of the Union. It had been used in the U.S. during the American Civil War in reference to the anticipated reconstitution of the Union. Hence, for a time, in American English, reconstructed "altered by Reconstruction" (1865).