uncontrolled (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.

early 15c., countrollen, "to check the accuracy of, verify; to regulate," from Anglo-French contreroller "exert authority," from Medieval Latin contrarotulus "a counter, register," from Latin contra "against" (see contra) + rotulus, diminutive of rota "wheel" (see roll (n.)). The word apparently comes from a medieval method of checking accounts by a duplicate register.

Un contrerollour qui doit contre roller au tresorere de la garderobe toutz lez receitez. [Household ordinances of Edward II, c. 1310]

Sense of "dominate, direct, exercise control over" is from mid-15c. Related: Controlled; controlling. Control group in scientific experiments is attested from 1952 (from a sense of control attested since 1875).