<p><strong>Verb</strong></p><ul><li>(used with object) to fill in: The old stream beds have been infilled with sediment.</li></ul><p><strong>Noun</strong></p><ul><li>The planned conversion of empty lots, underused or rundown buildings, and other available space in densely built-up urban and suburban areas for use as sites for commercial buildings and housing, frequently as an alternative to overdevelopment of rural areas.</li></ul><p><strong>Adjective</strong></p><ul><li>Of, relating to, or involving the use of infill in urban planning: infill condominium projects; infill office buildings and retail space.</li></ul>