As adjectives the difference between impolite and abrupt

is that impolite is not polite; not of polished manners; wanting in good manners while abrupt is {{context|obsolete|rare|lang=en}} broken away (from restraint) {{defdate|attested only in the late 16th century}}{{reference-book | last =| first = | authorlink = | coauthors = | editor =brown, lesley | others = | title = the shorter oxford english dictionary | origdate = | origyear = 1933| origmonth = | url = | format = | accessdate = | accessyear = | accessmonth = | edition = 5th | date = | year =2003| month = | publisher =oxford university press | location =oxford, uk | language = | id = | doi = | isbn =978-0-19-860575-7 | lccn = | ol = | pages =8| chapter = | chapterurl = | quote =}}.

As a verb abrupt is

{{context|transitive|archaic|lang=en}} to tear off or asunder {{defdate|first attested in the mid 17th century}}.

As a noun abrupt is

{{context|poetic|lang=en}} something which is [[#adjective|abrupt]]; an abyss {{defdate|first attested in the mid 17th century}}.