quilted mattress pad; quilted bed pad
A padded, often quilted, sheet-like cover placed on top of a mattress for comfort or protection. Common in Japanese bedding.
新しい敷きパッドを買って、ベッドがふかふかになった。
I bought a new quilted mattress pad, and the bed became soft and fluffy.
敷きパッドは洗濯機で洗えますか？
Can the quilted pad be washed in a washing machine?
Compound of 敷き (shiki, 'laying, spreading', from verb 敷く) + パッド (paddo, from English 'pad').