(1):

(a.) Contrary to, or offending against, the rules of propriety or good breeding; guilty of, or prone to, rude, unbecoming, or uncivil words or actions; as, an impertient coxcomb; an impertient remark.

(2):

(a.) Trifing; inattentive; frivolous.

(3):

(n.) An impertinent person.

(4):

(a.) Not pertinent; not pertaining to the matter in hand; having no bearing on the subject; not to the point; irrelevant; inapplicable.