Teriyaki is used to describe any chicken, beef, fish, etc. marinated in or served with teriyaki sauce.  Teriyaki sauce is typically made of soy sauce, sake, sugar and ginger.   So essentially, it is a dish, flavor, and sauce all with an interesting history. The word "Teriyaki" is Japanese, and describes the method of cooking:  yaki- means grilled, and teri refers to a shine given from the sugar, so the direct simplistic translation is "shine-grilled." Although the word teriyaki is of Japanese origin, teriyaki cooking is actually tied to Hawaiian roots.  It is believed that Japanese immigrants in Hawaii used the local foods there and came up with teriyaki, and if you've been to a Hawaiian barbecue, you'll know the deliciousness I'm talking about. The first Hawaiian/Japanese people used pineapple juice as their sugar and acid to get the shine while Japanese soy sauce remained the main ingredient.  So teriyaki chicken has its origins in japan ... and Hawaii.  It is a blend of two great cultures and one of the best blends of simple ingredients in the world!