Rendering into Roman letters words, terms, or characters from another writing system such as Chinese characters, Japanese hiragana and katakana and so on.

Katakana by the way, is a script for rendering foreign loan words into Japanese, so is much like romanization which, also by the way, is known as romaji.

Pinyin is the official Chinese government romanization method, while the older Wade-Giles system is still used for many names.