How universal is the term ‘shotgun’ for a vehicle’s front passenger seat?

In My Humble Opinion
41

My 8 year old says it all the time.

42

Yep. That is what the term means to me- and Google.

A jump seat (sometimes spelled jumpseat) is an auxiliary seat in an automobile, train or aircraft,[1] typically folding or spring-loaded to collapse out of the way when not used. The term originated in the United States c. 1860 for a movable carriage seat.[2]