Synonyms of fill-in

fill-in 1 of 2

noun

ˈfil-ˌin 

as in substitute

a person or thing that takes the place of another

I'm just a fill-in, so I have no idea where office supplies are kept

Synonyms & Similar Words

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

fill in

2 of 2

verb

1

as in to inform

to give information to

my friend quickly filled me in on the portion of the movie that I had missed

Synonyms & Similar Words

• inform
• tell
• advise
• catch up
• instruct
• brief
• teach
• educate
• clue (in)
• hip
• familiarize
• enlighten
• keep (someone) posted
• verse
• apprise
• wise (up)
• let someone know
• clear
• acquaint
• notify
• alert
• disclose (to)
• announce (to)
• advertise
• convince
• lecture
• assure
• reassure
• certify
• school
• warrant
• tutor
• undeceive
• disabuse
• disillusion
• disenchant

Antonyms & Near Antonyms

• mislead
• misinform

2

as in to substitute

to serve as a replacement usually for a time only

she's only filling in while the regular secretary is on vacation

Synonyms & Similar Words

• substitute
• stand in
• take over
• step in
• cover
• spell
• sub
• pinch-hit
• double (as)
• relieve
• understudy

Example Sentences

Recent Examples of fill-in

Noun

Based on the current fill-in rotation, Isola and Mina Kimes would be among the most plausible candidates. — Bobby Burack Outkick, FOXNews.com, 20 Aug. 2026

Gibbons, now 76, and Francis will continue to perform as ZZ Top and will resume the group’s postponed tour with a date in Austin, Texas this weekend with a fill-in drummer, a rep confirms to Variety. — Steven J. Horowitz, Variety, 18 Aug. 2026

Verb

And today’s LLMs are able to call on other computational modules to fill in their weak spots, so language is the gateway to ever-broader capacity. — George Musser, Scientific American, 17 Sep. 2026

With one cohost out (temporarily), iconic daytime series The View is bringing back multiple former cohosts to fill in at the Hot Topics table over the next few weeks. — Joey Nolfi, Entertainment Weekly, 17 Sep. 2026