Looking up...
back someone up
/bæk ˈsʌmwʌn ʌp/◆phrasal verb
support or defend
When the manager accused him of being late, his coworkers backed him up.
His coworkers supported his claim that he was not late.
informal
To support or defend someone, especially by providing evidence or testimony.
She backed up her friend during the argument by saying she saw what happened.
She supported her friend's version of events.
The witness backed up the victim's story in court.
The witness confirmed the victim's account.
Often used in contexts where someone's claims or actions are being questioned or challenged.
informal
To provide assistance or backup to someone.
I’ll back you up if you need help with the presentation.
I will assist you if you require help.
Can imply both moral and practical support.
Collocations
back someone upsupport or defend someoneback up a claimsupport a statement with evidenceback someone up in an argumentsupport someone during a dispute
Antonyms
Related Phrases
Pro Tip
Usage in Formal vs. Informal Contexts
In formal settings (e.g., legal or professional), use 'corroborate' or 'support' instead of the phrasal verb. For example, 'The evidence corroborates the witness's testimony' sounds more professional than 'The evidence backs up the witness's testimony.'
Gold Rule
Avoid Overuse
While 'back someone up' is versatile, overusing it can make speech sound informal or repetitive. Vary your phrasing depending on the context.
Word Origin
The phrase combines 'back' (to provide support) and 'up' (to reinforce or assist), originating in the early 20th century as a metaphor for providing physical or moral backing.
Usage Notes
Common in both casual and formal contexts, though more frequent in informal speech. Often used in legal, workplace, or social scenarios where credibility or assistance is needed.
Word Breakdown
back
to provide support or reinforcement
rootsomeone
the person being supported
pronounup
to reinforce or assist further
particleEnglish Dictionary