Back Up

1. To walk or drive a vehicle backwards.

Examples: Wait, back up! You drove past the house.
I asked the lady to back up because she was standing too close to me in line.

2. When you support someone or something.

Examples: Rita’s argument about global warming would’ve been great, if she had backed it up with some facts.
The secret to a great marriage is to always back each other up, even when the person is wrong.

3. To make a copy of computer data or files.
[Part. Adj/Attributive Noun] {Backup} Something else you have in case the main plans, file, equipment, etc. goes wrong.

Examples: You need to back up all your programs before you reformat your computer.
Do you have a backup date to the prom?
I have two cell phones because I need one for backup.

4. When something is prevented from moving.

Examples: Traffic is backed up on I-90 East.
This is the third time this week the drain has been backed up.

See our complete list of English phrasal verbs.