Infill (noun)

1. The act or process of filling in an empty space or gap.
2. Material used to fill in a space or gap.
3. The development of land within an existing built-up area.

Origin:

From the verb infill, meaning to fill in an empty space or gap, it can also be used as a verb form.

Examples:

1. The infill of the empty lots will help to revitalize the neighborhood.
2. The infill material used to level the ground was a mixture of sand and gravel.
3. Infill development is a way to make better use of existing infrastructure.
4. The infill of the wall was done with concrete.
5. The infill process will make the land suitable for building.