Definition from macmillandictionary.com
If I ask for more money will you back me up?
All the evidence backs up her story.
Traffic is backing up on all out-of-town routes.
Cars were backed up for miles.
Orders are really backed up this month.
I need everyone to back up about 10 paces.
See if you can back up a bit further.
I’ll back the car up the driveway.
Back up: didn’t you say they had already met?