extenuation (n.)

early 15c., extenuacioun, "action or process of making or becoming thin," from Latin extenuationem (nominative extenuatio) "a lessening, diminution," noun of action from past-participle stem of extenuare "lessen, reduce, diminish," from ex "out" (see ex-) + tenuare "make thin," from tenuis "thin," from PIE root *ten- "to stretch." From 1610s as "act of making less in importance or degree, a diminishing (as of blame or guilt) in fact or estimation, mitigation."