The dictionary isn't going to help, Doug. Fact is, usage has overcome your dictionary definition of "specular," just as usage, unfortunately, has overcome the correct meaning of "begs the question." Nowadays the dictionary is descriptive rather than prescriptive, and on this point it's a notch or two behind the degradation of the language.
But definitions, dictionary or otherwise, don't really matter. The idea that a properly exposed sun is a yellow disk just doesn't fit the physics of the situation. What you're telling me is that the sun emits more green and red light than blue. The fact is that the sun emits white light, which maxes out all three color channels. It's true that red and green are transmitted through the atmosphere slightly more readily than blue, so there's a very slight yellow shift through a clear sky, but atmospheric conditions would have to be perfect for the naked sun to appear yellow in a photograph.
Try paisley. I won't embarrass you by laughing in public.