A "nincompoop" is a term used to describe a person who is foolish or silly. It often implies a lack of common sense or intelligence in a light-hearted or humorous way. The word has been in use since the 17th century and is considered informal. The origin of "nincompoop" is somewhat unclear, but it may derive from the Latin phrase "non compos mentis," meaning "not of sound mind." While it can be used to poke fun at someone's actions, it is generally not meant to be deeply insulting.