One's general appearance or personality, as in I don't like the cut of Ben's jib. In the 17th century the shape of the jib sail often identified a vessel's nationality, and hence whether it was hostile or friendly. The term was being used figuratively by the early 1800s, often to express like or dislike for someone.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.