fill-in

1 of 2

noun

ˈfil-ˌin 

: someone or something that fills in

fill in

2 of 2

verb

filled in; filling in; fills in

transitive verb

1

: to enrich (something, such as a design) with detail

2

: to give necessary or recently acquired information to

I'll fill you in

intransitive verb

: to fill a vacancy usually temporarily

interns filled in for regular staffers

Synonyms

Noun

• substitute
• replacement
• backup

Verb

• inform
• tell
• advise
• catch up

Examples of fill-in in a Sentence

Noun

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

Verb

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

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

Recent Examples on the Web

Noun

Walsh joined Channel 58 as a reporter and fill-in anchor in April 2013. —Chris Foran, jsonline.com, 8 July 2025

After 24 games there and two fill-in games at AA Chesapeake, he was reassigned to the organization’s Florida Complex League team, which plays in Sarasota. —Joseph Wilkinson, New York Daily News, 18 June 2025

Verb

Dwight McNeil filled in there against both Accrington and Blackburn, but is a partial fit at best. —Patrick Boyland, New York Times, 21 July 2025

The precise effects are hard to predict because other funders may fill in some of the gaps. —Brian Stelter, CNN Money, 18 July 2025

Word History

First Known Use

Noun

1917, in the meaning defined above

Verb

1840, in the meaning defined at transitive sense 1

Rhymes for fill-in

• akin
• auxin
• buckskin
• chagrin
• deerskin
• foreskin
• fuchsin
• herein
• kingpin
• linchpin
• pigskin
• pinyin

Kids Definition

fill in

verb

1

: to furnish with specified information

fill in an application

filled us in on the latest news

2

: to fill a vacancy usually temporarily : substitute

filled in during the emergency