Bokeh is the soft out of focus background you get when you shoot a subject using a wide aperture, and the background is far enough away from the subject to be well outside the DOF limit.
Bokeh comes from the Japanese word boke, which means “blur” or “haze”, or boke-aji, the “blur quality.” Bokeh is pronounced BOH-KÉ™ or BOH-kay.
Specular highlights in the background then to take on a specific shape, either round, hexagonal or octagonal. This shape is dictated by the diaphragm blades of the lens aperture. The more rounded the blades are, the rounder the highlights. The straighter the blades the more hexagonal or octagonal are the highlights.
Sometimes the word bokeh is used to specifically describe these out of focus highlights, but in general is used to describe the while soft out of focus background.
Because the highlights depict the shape of the aperture, the look of the blurred background is really a characteristic of the given lens, and different lenses from different manufacturers will render the same scene differently.