A text expander allows you to use "shortcuts" when you type, so that, for example, you can type the letters "cy" and those letters will expand to "company."
Word provides AutoCorrect, and WordPerfect provides QuickCorrect.While both of these features were originally intended to make automatic corrections to incorrectly typed words -- for example, changing "adn" to "and" -- they can also be used as text expanders by adding entries such as the example in the paragraph above.