- to provide active aid to someone
- to provide an armed response or protection
- to be guarding something (usually vehicles) by being present up-front
- This politician is a sitting shotgun for his brother's company. It is sad to see that he is using his political influence for his own purposes.
- I am a sitting shotgun for my sister's gold ornaments until she comes back from the trip.
The phrase originates from the synonym "riding shotgun" in the early 1900's from the American west. A person armed with a shotgun (he would also be called the shotgun) would travel alongside coaches for short or long distances in order to be able to ward off any Indians or bandits that may attack and rob the occupants. In the later years when automobiles became popular, the shotgun would sit beside the driver doing the same thing. The trade was more popular for vehicles carrying either bullion or cash and hence would need the added security. So if the shotgun was not present then it would mean that there is nothing of value being transported, it would just be passengers. Recently the term is used in the gaming world.
- riding shotgun