1 A2 neutral
To reverse a vehicle.
"Could you back up a few metres so I can get through?"
inseparable
back up
A2 neutral separable transitive/intransitive
To reverse a vehicle; to support or confirm someone's statement; to create a copy of data; or to form a blockage.
In plain English
To drive backwards, to say that someone is telling the truth, or to make a copy of your files.
What does "back up" mean?
4 meanings, ordered from most common to least. Color-coded by CEFR level.
2 B1 idiomatic neutral
To support or confirm what someone has said; to provide evidence for a claim.
"Can anyone here back up his story about where he was that evening?"
separable
3 A2 neutral
To make a copy of data or files for safety.
"Always back up your work before updating the software in case something goes wrong."
separable
4 B1 idiomatic neutral
To become blocked or congested (traffic, drains, etc.).
"Traffic backed up for miles after the accident on the motorway."
inseparable
Literal vs figurative
Words literally mean
To move backwards and up (as in reversing a vehicle).
Actually means
To drive backwards, to say that someone is telling the truth, or to make a copy of your files.
Usage tip
One of the most versatile phrasal verbs in English with multiple distinct senses. Very frequent in everyday speech. The data/computing sense ('back up your files') is extremely common in modern usage. 'Backup' (noun/adjective) is the standard written form of the compound.
Words that pair with "back up"
Natural word combinations native speakers use most often.
data files claim story traffic evidence
How to conjugate "back up"
The five tense forms you'll use most often.
Base
back up
I/you/we/they
3rd person
backs up
he/she/it
Past simple
backed up
yesterday
Past participle
backed up
have + pp
-ing form
backing up
continuous
Hear "back up" in the wild
Listen to native speakers using "back up" in real YouTube videos — click a clip to watch it on Looplines.
Keep exploring
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