In dictionaries:
The Back-up Plan
(previously known as Plan B) a 2010 American romantic comedy film directed by Alan Poul, starring Jennifer Lopez and Alex O'Loughlin.
Back-up beeper
A back-up beeper, also known as back-up alarm or vehicle motion alarm, is a device intended to warn passers-by of a vehicle moving in reverse.
Back-up partner
A back-up partner, standby lover, or spare-tyre lover is a person anticipated as a potential future romantic/sexual partner in the event of the failure or unforeseen end of a current relationship.
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