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

These should be attractive, practical and scaled for infill. —Jacob Mitchell, San Diego Union-Tribune, 21 Apr. 2026

Rather than recreating the Eames House, the new Pavilion System distills its essential elements—the grid, the interplay of structure, and the infill—into something that can be built, adapted and deployed across different environments. —Kieron Marchese, Architectural Digest, 14 Apr. 2026

The pilot prioritizes infill development on existing lots, which may include an existing house, and typically limited to three or fewer units, spokesperson Meg Ralph told The Star. —Taylor O'Connor, Kansas City Star, 12 Apr. 2026

The new law expands and simplifies when an infill exemption applies. —Stephen Hobbs, Sacbee.com, 9 Apr. 2026

Word History

First Known Use

1939, in the meaning defined at sense 1

Rhymes for infill

• sinful