The policeman called for 'backup' [=called for other police to come and help him] because the suspect was carrying a gun.
There was a traffic 'backup' [=('Brit') 'tailback'] for miles on the road because of the accident.
His role on the team is to be a 'backup' to the regular quarterback.
(..) - Please. Three guys up at the gate-- Two visible, one in the blind. We got five guys down here with a backup out of sight. I got Tyrus down in the treeline with a Barret .. Planted him there last night in case we had (..)2011 TvShow: Breaking Bad Title: Problem Dog Season: 4 Episode 7