What is "dumb insolence"

n. (context British military English) The offence of refusing to answer the questions of an officer.

Dumb insolence is an offence against military discipline in which a subordinate displays an attitude of defiance towards a superior without open disagreement. It is also found in settings such as education in which obedience and deference to a teacher is expected but may be refused by unruly pupils. For example, a pupil may suck their teeth, sigh or walk away while being spoken to.