back up

verb

1. (tr) to support or assist

2. (intr) cricket (of a nonstriking batsman) to move down the wicket in readiness for a run as a ball is bowled

3. (of water) to accumulate

4. (of traffic) to become jammed behind an accident or other obstruction

5. computing to make a copy of (a data file), esp for storage in another place as a security copy

6. printing to print the second side of (a sheet)

7. to repeat an action immediately

noun

1. a support or reinforcement

2. 1. a reserve or substitute

   2. ( as modifier )

      backup troops

3. 1. musical accompaniment, esp for a pop singer

   2. ( as modifier )

      backup singer

4. the overflow from a blocked drain or pipe

5. computing a file or set of files copied for security purposes

Idioms and Phrases

Move or drive a vehicle backward, as in He told her to back up into the garage . [First half of 1800s]

Bring or come to a standstill, as in The water had backed up in the drains , or The accident had backed up traffic for miles . [First half of 1800s]

Support or strengthen, as in The photos were backed up with heavy cardboard so they couldn't be bent , or I'll back up that statement of yours . [Second half of 1700s]

Duplicate a file or program so that the original is not lost. For example, Every computer manual warns you to back up your work frequently in case of a power outage or computer failure . [Second half of 1900s]

Related Words

• fall back 
• retreat