The term 'FILLS IN THE GAPS?' can be solved by the crossword solution CAULKS (6 letters). Caulking is a process of sealing joints or seams in various structures and materials, such as walls, roofs, windows, and pipes. It is done using a variety of materials, such as silicone, acrylic, latex, and polyurethane. Caulking is used to prevent water, air, and other elements from entering the structure, thus providing insulation and protection.