An instance of missorting; something, especially a letter, which has been missorted.
Late 19th century; earliest use found in The Daily News. From missort.
with object To allot to a wrong place in sorting; (now) (specifically of mail) to sort incorrectly.
Late 16th century; earliest use found in Richard Mulcaster (?1532–1611), schoolmaster and author. From mis- + sort.