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

Hollywood icon Rosie O’Donnell has taken stock of — and shots at — the television landscape before making her temporary return to the talk show format as fill-in host of Jimmy Kimmel Live. — Joey Nolfi, Entertainment Weekly, 17 Aug. 2026

In fairness to all the backup tackles, Larry Borom struggled at this point last season, then became a decent fill-in starter for Jackson when he was sidelined by his foot injury. — Omar Kelly, Miami Herald, 9 Aug. 2026

Verb

Part of the issue is that as the economic hardships continue, more people are adding to their debt loads by turning to expensive, short-term borrowing options, like credit cards, to fill in the gaps. — Angelica Leicht, CBS News, 20 Aug. 2026

Gasper has filled in admirably for Yoshida, homering in his third straight game Wednesday. — Jen McCaffrey, New York Times, 20 Aug. 2026