Completing partial words
In TextEdit, you can view a list of possible completions for a selected word.
Position the text cursor at the end of a partial word or a complete word.
Choose Edit > Complete (or press Option-Esc), then select a word from the list.
If you try a partial word (such as "ret"), you will see options such as "retire," "return," or "retrieve." If you try a complete word (such as "return"), the list of options will include more specific words, such as "returning" and "returned."