Origin and history of impunity

"of or pertaining to punishment by law," mid-15c., from Old French peinal (12c., Modern French pénal) and directly from Medieval Latin penalis, from Latin poenalis "pertaining to punishment," from poena "punishment," from Greek poinē "blood-money, fine, penalty, punishment," from PIE *kwoina, from root *kwei- "to pay, atone, compensate" (source also of Greek timē "price, worth, honor, esteem, respect," tinein "to pay a price, punish, take vengeance;" Sanskrit cinoti "observes, notes;" Avestan kaena "punishment, vengeance;" Old Church Slavonic cena "honor, price;" Lithuanian kaina "value, price").

"unpunished" (obsolete), 1610s, from Latin impunis "unpunished" (see impunity). For the word meaning "attack by argument," see impugn.

word-forming element meaning "not, opposite of, without" (also im-, il-, ir- by assimilation of -n- with following consonant, a tendency which began in later Latin), from Latin in- "not," cognate with Greek an-, Old English un-, all from PIE root *ne- "not."

In Old French and Middle English often en-, but most of these forms have not survived in Modern English, and the few that do (enemy, for instance) no longer are felt as negative. The rule of thumb in English has been to use in- with obviously Latin elements, un- with native or nativized ones.