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

One approach is to use what is commonly called infill development, which utilizes underused land within existing urban areas to increase housing density without expanding the city’s footprint. —Destiny Torres, Orange County Register, 4 Oct. 2024

The infill development project also encompasses the extension of Kickapoo Street, which will terminate in a cul-de-sac. —Tammy Ljungblad, Kansas City Star, 10 June 2025

The area is often described as one of the country’s largest urban infill projects, and economic development leaders see it as a means of doubling the size of Sacramento’s downtown. —Annika Merrilees, Sacbee.com, 5 June 2025

However, today there are alternative infill materials available, including organic options such as cork or walnut shells. —Colleen Sullivan, Better Homes & Gardens, 14 Apr. 2025

Word History

First Known Use

1939, in the meaning defined at sense 1

Rhymes for infill

• sinful