Here's a list of some nations and regions, with their names in Chinese. Note that the country's name can also be used as an adjective. For example, 日本货 (rìběn huò) means "Japanese goods," and is derived from 日本 (rìběn; Japan) and 货 (huò; goods). As an aside, China imports a good number of products from Japan. Between 2001 and 2007, it was the greatest exporter to China, beating the European Union, South Korea, and Taiwan.^[1] You could also say 日本椅子 (rìběn yǐzi; Japanese chair), 日本食品 (rìběn shípǐn; Japanese food products), and 日本动画片 (rìběn dònghuà piàn; Japanese cartoons). Terms like these can be shortened, for example, 日货 means the same thing. You can see 日 is an adjective which means "pertaining to Japan," i.e., "Japanese." Another way to describe its function is that it acts like a "root," much like in English. Headlines are often abbreviated this way. For example, 中俄合作 (zhōng é hézuò) can mean "China and Russia cooperate" or "Sino-Russian cooperation." In common conversation, however, excessive abbreviation is undesirable, because it often leads to ambiguity.

References

Asia 亚洲 / 亞洲 Yàzhōu

Oceania 大洋洲 Dàyángzhōu

America 美洲 Měizhōu

Europe 欧洲 / 歐洲 Ōuzhōu

Africa 非洲 Fēizhōu