insulation.

Material or a construction layer that reduces the passage of heat, sound, or electricity.

Use it for

Words that belong together

• roof insulation
• acoustic insulation
• add insulation

On the page

Loose insulation spilled from the opened ceiling.

They added roof insulation before converting the attic.

Thin acoustic insulation allowed the neighbour's radio to remain audible.

Usage notes

Primary category: architecture. Specify thermal or acoustic where needed; insulation does not automatically make a room entirely soundproof. Mass noun; no ordinary plural in material sense.