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.
(..) We gotta get indoors. Follow me. Lowery, we're headed your way. Call in a chopper. Everything must be accounted for. I want all backup generators online. Where have you been? Change of plans. Mission took a jog to the left. I'm taking everything off-site. The embryos are safe here. (..)2015 Jurassic World