noun

insolent or impertinent behaviour.

one juror had the effrontery to challenge the coroner’s decision

impudence,impertinence,cheek,insolence,cheekiness,audacity,temerity,brazenness,forwardness,front,presumption,nerve,gall,pertness,boldness,shamelessness,impoliteness,disrespect,bad manners,unmannerliness,overfamiliarity,answering back,talking back,brass,brass neck,neck,face,lip,mouth,cockiness,sauce,snash,sass,sassiness,nerviness,chutzpah,back talk,hide,crust,backchat,malapertness,contumely,procacity,assumption,dare,make so bold as,be so bold as,presume,have the temerity,have the audacity,have the nerve,be brave enough,have the courage,go so far as,take the liberty of