Insolent means rudely disrespectful to those owed respect. An insolent reply, insolent behaviour, don't be insolent.
It implies a hierarchy: you can only be insolent to somebody above you, which is why it belongs to schools, courts and the forces and sounds archaic elsewhere. The Latin behind it means unaccustomed, and from there immoderate and then arrogant.
1adjectiveinsolentRudely disrespectful to those owed respect.
“The insolent pupil yawned loudly while the head teacher was speaking.”
insolent is a quality.
Latin insolens means unaccustomed or immoderate — in, not, plus solere, to be used to.
Proto-Indo-European
*dʰeh₁-
Latin
īnsolēns — unaccustomed, unwanted, unusual, immoderate, excessive, arrogant, insolent
English, today
insolent
Built from
From Middle English -, from Old French -, from Latin īnsolēns (“unaccustomed, unwanted, unusual, immoderate, excessive, arrogant, insolent”), from in- + solēns, present participle of soleo (“to be accustomed, to be wont”).
Etymology from Wiktionary, CC BY-SA