to lessen the seriousness or extent of (a crime, etc), esp by providing a reason or excuses
extenuating circumstances
to make (somebody) thin or emaciated
to dilute or weaken (something)
extenuation /-ʹaysh(ə)n/ noun
extenuator noun
extenuatory /-ət(ə)ri/ adj
[Latin extenuatus, past part. of extenuare, from ex-1 + tenuis thin]