glass wool

American  

noun

1. spun glass similar to wool, used for insulation, filters, etc.

---

glass wool British  

noun

1. fine spun glass massed into a wool-like bulk, used in insulation, filtering, etc

---

Etymology

Origin of glass wool

First recorded in 1875–80

Example Sentences

Mid and East Antrim Borough Council said building regulations introduced in the 1970s led to the widespread use of safe insulation materials like glass, wool and fibreglass.

From BBC • Mar. 25, 2026

McKinley favored high tariffs on goods like steel, iron, glass, wool, sugar and beans as a way to protect and expand American industry.

From New York Times • Dec. 6, 2018

On the ceiling, sound is absorbed by 2 in. of glass wool surfaced with vinyl.

From Time Magazine Archive

The glass house also contains another important Owens-Illinois product: spun glass, or glass wool, woven into thick mats and used as insulator of heat and sound.

From Time Magazine Archive

The long tube is bent down outside the flask, and is here provided with a small bulb tube containing glass wool or asbestos.

From Scientific American Supplement, No. 497, July 11, 1885 by Various