air foam
/ˈɛː fəʊm/noun
1Originally British. A water-based foam used in firefighting.
2 North American. Originally: a sponge-like rubber material used as padding in furniture, mattresses, and vehicle seating. Now: (a trademark for) a type of flexible synthetic padding material.
Origin
1930s; earliest use found in Nashua (Iowa) Reporter. From air + foam, apparently so called on account of its consistency.