a person or thing that fills in, as a substitute, replacement, or insertion.
The company used a fill-in for workers on vacation.
a brief, informative summary; a rundown.
(tr) to complete (a form, drawing, etc)
(intr) to act as a substitute
a girl is filling in while the typist is away
(tr) to put material into (a hole or cavity), esp so as to make it level with a surface
informal (tr) to inform with facts or news
slang (tr) to attack and injure severely
a substitute
informal a briefing to complete one's understanding
Complete something, especially by supplying more information or detail. For example, Be sure to fill in your salary history . It is also put as fill in the blanks , as in We'll rely on Mary to fill in the blanks . Yet another related usage is fill someone in , as in I couldn't attend, so will you fill me in? The first term dates from the mid-1800s; the others from the first half of the 1900s. Also see fill out .
Also, fill in for . Take someone's place, substitute for. For example, The understudy had to fill in at the last minute , or I can't come but my wife will fill in for me . Also see fill someone's shoes .
First recorded in 1915–20; noun use of verb phrase fill in
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
When their All-Star forward Jalen Williams suffered a hamstring injury, they had an appropriate fill-in to call upon: a backup big man named, coincidentally, Jaylin Williams.
From The Wall Street Journal ● May 7, 2026
She is a frequent fill-in for “CBS Mornings” co-host Gayle King.
From Los Angeles Times ● Jan. 9, 2026
He will also serve as a lead correspondent for “48 Hours,” contribute to “60 Minutes,” and act as a fill-in anchor for CBS’s flagship broadcasts, she said.
From The Wall Street Journal ● Dec. 9, 2025
Cummins may return for the second Test, and for now Scott Boland is a capable fill-in with an outstanding record in Australia.
From BBC ● Nov. 5, 2025
He was a kind of fill-in speaker, a holy handyman.
From "Go Tell It on the Mountain" by James Baldwin
McElwee finds images both startling and serene; videos that fill in gaps he couldn’t on his own.
From Salon ● Jul. 24, 2026
The findings help fill in the missing steps of a larger cycle.
From Science Daily ● Jul. 18, 2026
For example, you could work 30 hours a week at the bar, then fill in at the yoga studio and take on consulting work when you have the bandwidth or need the extra cash.
From MarketWatch ● Jul. 13, 2026
He’s 6-foot-2, a gifted header of the ball, and can fill in all over the park.
From The Wall Street Journal ● Jul. 11, 2026
A small chain of memories that fill in one tiny part of my life.
From "The Adoration of Jenna Fox" by Mary E. Pearson
So last winter they felt comfortable trading Mark Delgado and Gastón Brugman, the two most likely fill-ins for Puig, largely to fit their payroll under the MLS salary cap.
From Los Angeles Times ● Jan. 6, 2026
Maxwell noted that his work had been covered by knowledgeable fill-ins from out of state.
From Salon ● Jul. 24, 2025
In one sense, Stewart is the latest in a line of celebrity fill-ins who have hosted “The Daily Show” since Trevor Noah left in December 2022.
From New York Times ● Feb. 13, 2024
McAvoy was one of three regulars on the blue line that the Bruins didn’t have, making the performance of fill-ins like rookie Lohrei even more impressive.
From Washington Times ● Nov. 3, 2023
The conga drum player was especially wild, playing insane fill-ins all over the place.
From "Drums, Girls, and Dangerous Pie" by Jordan Sonnenblick
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
