Impertinence, n.
Etymology: [Cf. F. impertinence. See Impertinent.]
1. The condition or quality of being impertnent; absence of pertinence, or of adaptedness; irrelevance; unfitness.
2. Conduct or language unbecoming the person, the society, or the circumstances; rudeness; incivility. We should avoid the vexation and impertinence of pedants who affect to talk in a language not to be understood. Swift.
3. That which is impertinent; a thing out of place, or of no value. There are many subtile impertinences learned in schools. Watts.
Shades of meaning
Fernald has no entry of its own for impertinence; he lists it under impudence, pertness.
Where he writes about it:
Impertinence primarily denotes what does not pertain or belong to the occasion or the person, and hence comes to signify interference by word or act not consistent with the age, position, or relation of the person interfered with or of the one who interferes; especially, forward, presumptuous, or meddlesome speech. — from impudence
Impudence is shameless impertinence. — from impudence
What would be arrogance in a superior becomes impertinence or impudence in an inferior. — from impudence
Impertinence has less of intent and determination than impudence. — from impudence
We speak of thoughtless impertinence, shameless impudence. — from impudence
Impertinence and impudence may be gross and stupid; pertness and sauciness are always vivid and keen. — from pertness