a cushion attached to the top of the back of an automobile's seat to prevent whiplash

In an automobile, the headrest or head restraint is a device attached to the top of the seat behind the occupant's head. Headrests became a common safety feature in most automobiles during the 1970s.

Optional headrests tor 1966 through 1968 models. J K

Curved piece of wood or stone on a vertical post, used as a pillow.

a rest for the head