Eyeglasses popular from the late 19th through early 20th century which lacked temples and were held on the face by pinching the nose, hence the name, pinch nose (Pince Nez is French). They were made in three main styles, a C or hoop bridge, fingerpiece with a hard bridge and spring loaded nosepads, or with a sliding telescoping bridge. Franklin D. Roosevelt wore these as did Woodrow Wilson.
Pince nez are spectacles without arms, so they are worn on the nose.
It literally means "pinch-nose." I'm assuming you already know that it refers to reading glasses designed to clip on the nose?
Pince nez is a type of eye glasses that has no piece connecting the glases to the ears of the wearer. "He adjusted his pince nez and inspected the document"