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 nounSt. 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.
Cite this Entry
“Infill.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/infill. Accessed 30 Sep. 2026.
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