back up

phrasal verb

Word Forms

present tense
I/you/we/they	back up
he/she/it	backs up
present participle	backing up
past tense	backed up
past participle	backed up

1
transitive (back someone up) to give support to someone by telling other people that you agree with them
If I ask for more money will you back me up?
Synonyms and related words
To support an idea, plan or person
support
back
get behind
2
transitive to show that an explanation or belief is probably true
All the evidence backs up her story.
Synonyms and related words
To show or agree that something is true
show
prove
point to
3
intransitive/transitive to make a copy of information on your computer
Synonyms and related words
To use or program a computer
access
archive
back up
4
intransitive/transitive if traffic backs up, or if it is backed up, the vehicles are in a long line and waiting to continue moving
Traffic is backing up on all out-of-town routes.
Cars were backed up for miles.
Synonyms and related words
Traffic movements and traffic jams
back up
bottleneck
bumper-to-bumper
1. 4a
  if a toilet, sink, or drain backs up, or if it is backed up, water cannot flow through it because something is blocking it
  Synonyms and related words
  Plumbing and drainage systems
  airlock
  back up
  blockage
2. 4b
  if a system backs up, or if it is backed up, it has slowed down or stopped working because there is too much of something for it to deal with
  Orders are really backed up this month.
  Synonyms and related words
  To stop working (of a piece of equipment)
  break down
  go off
  shut off
5
intransitive to move backwards a short distance
I need everyone to back up about 10 paces.
Synonyms and related words
To move, or to move something away or back
back away
draw back
part
6
intransitive/transitive to make a car go backwards
See if you can back up a bit further.
back something up something:
I’ll back the car up the driveway.
Synonyms and related words
To drive, or to operate a vehicle
back up
belt up
be on someone’s tail
7
intransitive mainly Americanused for telling someone to return to something that was said earlier
Back up: didn’t you say they had already met?
Synonyms and related words
Ways of asking someone to say something again
I’m sorry
pardon me
excuse me