1.VerbTo accompany the driver of a vehicle on a journey as an armed escort (originally with a shotgun); to accompany someone in order to assist and protect.
"He attended the meeting to ride shotgun for the sales team, in case anyone had a technical question."
2.VerbTo ride in the front passenger seat of a vehicle, next to the driver.
"When both kids want to ride shotgun with Mom, they’ll just have to take turns."
3.VerbTo supervise a process and watch for any risks.