Some people use a term for a popular special case in place of a generic term. (Often this popular special case is a particular product in that category.) I think that this is a common phenomenon. Is there any word/phrase for it?
For example, “Coke” officially refers to a Coca-Cola (I think), but some people seem to call any carbonated soft drinks “Coke.” In Japanese, famikon is the Japanese name for Nintendo Entertainment System (NES), a video game console which was extremely popular in 1980s and early 1990s, but some Japanese people call any video game console famikon even if it is not really a famikon. (As an aside, calling a video game console famikon when it is not really a famikon is even a stereotype of a “mother unfamiliar with technology” in Japan.) I am looking for a term which refers to this kind of usage of words.