Concealed weapons are weapons, especially handguns, which are kept hidden on one's person, or under one's control. Carrying a concealed weapon is illegal in most states unless the party with the weapon is a law enforcement officer or has a permit to carry a concealed weapon. Some states allow citizens to carry a concealed weapon, while allowing places open to the public to post a notice banning concealed weapons on the premises. Requirements for permits to carry a concealed weapon vary by state, but they usually require a minimum age, completion of a safety course, and prohibit felons or those found mentally unstable or guilty of certain crimes to obtain a permit, among other requirements. A number of states allow law-abiding citizens to carry concealed weapons after obtaining the proper permits. These are often referred to as "concealed carry" laws. For example, one state allows a concealed carry permit to be issued to anyone who is at least 21 years old, has lived in the state at least 45 days, the county or adjacent county for 30 days, completes a 12-hour firearms training course, and passes criminal and mental-health background checks. As of this writing, only six U.S. states do not have a concealed carry law. Laws vary by state, so local laws should be consulted for requirements in your area. The following is a state law defining a concealed weapon: 62.1-04-01. Definition of concealed. A firearm or dangerous weapon is concealed if it is carried in such a manner as to not be discernible by the ordinary observation of a passerby. There is no requirement that there be absolute invisibility of the firearm or dangerous weapon, merely that it not be ordinarily discernible. A firearm or dangerous weapon is considered concealed if it is not secured, and is worn under clothing or carried in a bundle that is held or carried by the individual, or transported in a vehicle under the individual's control or direction and available to the individual, including beneath

Any weapon carried around but not visible, eg. a gun in your coat pocket.

A concealed weapon is one not in plain sight. A gun in someone's car would be a concealed weapon.