Synonyms of back (up)

back (up) 1 of 3

verb

1

as in to testify (to)

Related Words

• testify (to)
• bear out
• vouch (for)
• witness
• verify
• validate
• confirm
• corroborate
• vindicate
• certify
• authenticate
• argue
• support
• substantiate
• attest
• guarantee
• warrant
• affirm
• avouch
• prove
• assert
• aver
• document
• reinforce
• declare
• establish
• profess
• avow
• demonstrate

Dissimilar Words

• disprove
• refute
• contradict
• rebut
• deny
• challenge
• contest
• question
• dispute
• gainsay
• disavow
• disclaim

2

as in to gel

Related Words

• gel
• coagulate
• harden
• set
• congeal
• clot

Dissimilar Words

• flow
• run
• stream
• pour
• arise
• roll
• issue
• race
• course
• spring
• emanate
• disembogue
• rush
• effuse

backup

2 of 3

noun

ˈbak-ˌəp 

1

as in jam

a crowded mass (as of cars) that impedes or blocks movement

there was the inevitable backup of travelers trying to pass through airport security

Synonyms & Similar Words

• jam
• bottleneck
• congestion
• tailback
• snarl
• jam-up
• lock
• traffic
• logjam
• delay
• tangle
• tie-up
• stoppage
• gridlock
• slowdown
• crawl

2

as in replacement

a person or thing that takes the place of another

you didn't get the lead position, but you can be the backup to the chosen singer

Synonyms & Similar Words

• replacement
• substitute
• assistant
• surrogate
• reserve
• stand-in
• relief
• sub
• cover
• fill-in
• pinch hitter
• designated hitter
• proxy
• alternate
• locum tenens
• deputy
• delegate
• second
• agent
• makeshift
• attorney
• stopgap
• factor
• representative
• successor
• apology
• assignee
• rep
• understudy
• commissary
• envoy
• procurator
• reliever
• superseder

backup

3 of 3

adjective

as in makeshift

Related Words

• makeshift
• proxy
• substitute
• alternate
• stopgap
• make-do
• acting
• interim
• temporary
• provisional
• ad interim
• jackleg
• provisionary
• provisory

Dissimilar Words

• permanent
• long-term

Example Sentences

Recent Examples of back (up)

Noun

The singer and her backup dancers took safety precautions for their footwear while on stage, adding detachable triangle shoe straps to their neon pumps. — Karla Rodriguez, Footwear News, 16 Oct. 2026

It was opened three minutes later, presumably so that the witnesses could see the effects of a second, backup dose. — Amy Davidson Sorkin, New Yorker, 16 Oct. 2026

Adjective

Already, larger batteries are paired with solar and wind projects, and homeowners are using smaller batteries to store excess energy from rooftop solar and for backup power. — ABC News, 20 Oct. 2026

In July 2022, Sguros was just a backup officer on a welfare check of Dennis West, 71, at his home in Lauderhill, the Broward Sheriff’s Office said. — Devoun Cetoute, Miami Herald, 20 Oct. 2026