Thesaurus.com
Dictionary.com
Definitions

back up

VERB
move backward
Synonyms
STRONGEST
fall back retreat
WEAK
abandon withdraw
Antonyms
STRONGEST
forge ahead
WEAK
continue defend pursue
VERB
support
Synonyms
WEAK
advance back champion confirm encourage help lend support promote pull for stand behind stand by
Antonyms
WEAK
continue defend pursue
ADJECTIVE
substitute
Synonyms
STRONG
alternate alternative another stand-in

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

"The police are on site. Back-up security teams have been deployed to reinforce safety on the line," it added.

From Barron's • Dec. 27, 2025

Back-up was drafted in from other jails to help bring the demonstrations to a peaceful conclusion, but the indiscipline highlighted major problems at Glenochil which are the subject of a new inspection report.

From BBC • Nov. 4, 2025

Released in time for Valentine’s Day, the movie is a rom-com “homecoming” for Lopez, known for films like “Maid in Manhattan”, “The Wedding Planner” and “The Back-up Plan”.

From Reuters • Feb. 9, 2022

Back-up quarterback Cameron Rising led the Utes’ improbable comeback, passing for 153 yards and three touchdowns while engineering three strong drives after replacing ineffective Charlie Brewer late in the third quarter.

From Seattle Times • Sep. 18, 2021

Back-up generators and evacuation chairs could be installed in buildings where people with disabilities live.

From The Verge • Feb. 26, 2021