Glossary
Memory foam (viscoelastic foam)
Polyurethane foam engineered to respond slowly to pressure, contouring to the body before recovering. Good pressure relief for side sleepers; the trade-offs are heat retention (unless gel or open-cell modifications work as claimed) and a 'stuck' feeling some sleepers dislike. Durability tracks density, just as with regular polyfoam.
Related: polyfoam · foam density