The word 'blue' most definately CAN be copyrighted - - - - Maybe just not by itself. Example: Jet Blue; Blue Sky Studios; Blue Sky Tex Systems; Blue Water Books; etc.
Originally Posted by HellasVagabond
When it was first announced it was called Blue-Ray, later on some companies decided to call it Blu-Ray.
Also, what do you mean by "Some Companies". Blu-ray is a SONY product. Sony OWNS Blu-ray. No other companty is involved in the ownership of Blu-ray.