infill

noun

in·​fill ˈin-ˌfil 

1

: material that fills in something (such as a hole or the spaces between a building's structural members)

volcanic infill

fiberglass infill

The artificial turf being used contains infill that is made from recycled tires …

—Greg Fitzpatrick

It's framed with hand-hewn cypress posts and beams, though instead of … brick infill … the walls are formed from … a mixture of mud, moss, and animal hair that was once used by native Americans living in the area.

—Amy R. Hughes

2

: new buildings constructed in the space available between existing structures

Urban infill, a big theme these days in city planning, is essentially the opposite of "urban sprawl." As cities grow, planners are looking for ways to pack more people into places that are already developed.

—Franklyn Cater

—often used before another noun

St. Louis must be the infill capital of the nation. Liberally scattered over the city, especially in the older parts, you see clumps and blocks of new apartments, condominia and row houses tucked in among centenarian neighbors.

—E. F. Porter

infill housing

infill verb, transitive + intransitive

infilled; infilling

… it was easier to achieve the vaults themselves by building them of a framework of ribs infilled with webs.

—James F. O'Gorman

Stump holes can be expected to infill with material from the pit walls and immediate vicinity …

—Jonathan D. Phillips et al.

Examples of infill in a Sentence

Recent Examples on the Web

Gradual infill should reduce disruption and backlash. —Phillip Molnar, San Diego Union-Tribune, 25 Dec. 2025

Building across the Kansas City area In previous years, Hicks said, Habitat focused on building infill houses on empty lots dotting neighborhoods. —Eric Adler december 22, Kansas City Star, 22 Dec. 2025

Willkommen is a mixed-use, mixed-income development that includes 16 historic rehabs and four new infill buildings across four sites in the neighborhood. —Randy Tucker, Cincinnati Enquirer, 20 Dec. 2025

Nearly one year after enacting a policy aimed at speeding up approvals for large-scale infill housing developments, San José has approved its first project under the new rules, cutting the permitting time by more than half. —Devan Patel, Mercury News, 3 Dec. 2025

Word History

First Known Use

1939, in the meaning defined at sense 1

Rhymes for infill

• sinful