back up

Back up means someone or something that is a substitute or reinforcement. (noun)

An example of back up is a second team of Navy Seals waiting to raid a compound if the primary team needs assistance.

Back up means to walk, drive or move in reverse. (verb)

An example of back up is for a truck to move in reverse to line up with a loading bay.

Back up means to copy or save computer data on a location other than your main computer hard drive. (verb)

An example of back up is when you copy your pictures to a CD.

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» back up synonyms

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