Entries linking to unrestrained
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.
mid-14c., restreinen, "to stop, prevent, curb" (a vice, purpose, appetite, desire), from stem of Old French restraindre, restreindre "to press, push together; curb, bridle; bandage" (12c.), from Latin restringere "draw back tightly, tie back; confine, check" (see restriction).
From late 14c. as "keep (someone or something) from a course of action," hence "keep in check or under control, deprive (someone) of liberty by restraint" (1520s). Related: Restrained; restraining; restrainer; restrainable.
That which we restrain we keep within limits; that which we restrict we keep within certain definite limits; that which we repress we try to put out of existence. [Century Dictionary, 1902]