the.com/electric blanket

means A blanket with built-in wires that warm it electrically, usually with adjustable heat settings, so you can toast a bed before or during sleep.

from A 20th-century invention straightforwardly named for what it is — electric plus blanket. Early versions built on 19th-century heating-pad and electrotherapy devices that wrapped warming wires in fabric for medical use; by the mid-1900s, with safer insulated wiring, the idea moved from clinic to bedroom and the compound name simply stuck.