For the U.S. anti-radiation missile, see AGM-122 Sidearm, you may also be looking for the article on Wakizashi, which translates to side arm

A side arm is a small personal weapon that is typically worn on the body in a holster in such a way to permit immediate access and use. Although this term can apply to swords and other mêlée weapons (called main-gauche or Wakizashi in this case), the modern use of it usually pertains to pistols and similar firearms.

A side arm is typically required equipment for law enforcement personnel and military officers. Usually, uniformed personnel of these services wear their weapons openly, while plainclothes personnel typically keep theirs under their outer clothes. However, in some military situations, military officers prefer not to have such a weapon visible as it can identify them as a priority target for snipers.

According to an adventure book written under the pseudonym S. M. Gunn, the Red Army was noteworthy because its officers hardly ever dispensed with their side arms (usually Makarov PMs), considering them equivalent to badges of office. It is unclear whether this tradition is maintained within the armed forces of the present-day Russian Federation, but it seems likely.

Firearms | Personal weapons | Seitenwehr