A shotgun wedding is a form of an arranged or forced marriage. It is an expression referring to a type of wedding which is arranged less out of the desire of the participants, but rather to avoid embarrassment due to an unplanned pregnancy. The phrase is considered American jargon, although it said to have been used in other parts of the world.
It derives from the alleged old southern custom of persuading the groom to marry the pregnant bride at gunpoint so he does not escape, hence, “shotgun wedding.”
As times have changed and society no longer shuns out-of-wedlock pregnancies, shotgun weddings are less common.