Insulate/ˈɪnsəleɪt/ Definition 1 of 3Pro Tip 1/3Physical Barrier Insulate implies a physical layer that acts as a barrier to heat, sound, or electricity. Adding foam to insulate the walls. Pro Tip 2/3Energy Efficiency Insulating your home can mean a practical step for saving energy and reducing bills. They decided to insulate the attic before winter. Pro Tip 3/3Safety Measure Insulating is also a safety measure, especially when dealing with electricity. All electrical wires have to be well-insulated.