Chinese

When used as an adjective, it refers to anything that is originated from China, e.g., Chinese cuisine.

When the word is used as a noun, it means either:

one of the Chinese languages.
Zhongguo ren (中國人 or 中国人): which is Chinese in a political sense and includes a person from the People's Republic of China. Whether or not the term includes a person from Taiwan is a controversial topic and depends on one's political beliefs.
Hua ren (華人 or 华人): a descendant of Zhongguo ren, including people of any nationality (e.g., Chinese Americans). See ethnic Chinese.

The two terms are generally used interchangeably within the People's Republic of China and among overseas Chinese in North America. Overseas Chinese in southeast Asia, particularly in Malaysia and Singapore, make a clear distinction between Hua ren (Chinese in the ethnic sense) and Zhongguo ren (Chinese in the political sense) as do supporters of Taiwanese independence within Taiwan.

When used by non-Chinese, the term has also been used synonymously with "the Han", which is the majority ethnicity (>92%) within China. Chinese themselves tend to reject this usage, and conflicts over these particular usage tend to come up in discussions about Tibet.