Opera window
An opera window is a small fixed window usually behind the rear side window of an automobile, originating with small windows mounted in the fabric of a folding top on horse-drawn carriages. They are typically mounted in an automobile's C-pillar, usually within a padded, vinylled section of the roof as a reference to the original location in a fabric roof. The design feature was popular, mainly with domestic U.S. manufacturers but also seen in Japan, during the 1970s and early 1980s..
The origin was from "opera" vehicles of around 1915 with occasional collapsible seating for extra passengers. The opera window was also a feature on "formal roof" and limousine models with higher than a normal roof to accommodate passengers with top hats.