fill-in

1 of 2

noun

ˈfil-ˌin 

: someone or something that fills in

She performed well as the emergency fill-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 of fill-in

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

The group hired a fill-in drummer, Dutch musician Bram van den Berg, for their residency at Las Vegas’ Sphere in 2023 and 2024. — Gil Kaufman, Billboard, 29 Sep. 2026

Multiple choice or fill-in-the-blank exam questions could be quickly and objectively scored. — Beth Kania-Gosche, The Conversation, 22 Sep. 2026

Verb

Hughes will likely be filling in while Watch Commander Tim Bradford is abducted. — Nellie Andreeva, Deadline, 11 Oct. 2026

Bruns has tattooed himself with PhotoTat, using the inks to fill in fish-scale designs on his legs. — Rupendra Brahambhatt, Interesting Engineering, 10 Oct. 2026

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
• crankpin
• deerskin
• foreskin
• fuchsin
• herein
• kingpin
• linchpin
• pigskin

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