You can view a list of possible completions for a partially entered word.
Position the insertion point at the end of a partial word.
Choose Edit > Complete (or press Option-Esc), and then select a word from the list.
If you try a partial word (such as “ret”), you’ll see options such as “retire,” “return,” or “retrieve.” If you try a complete word (such as “return”), a narrower list of options will appear, such as “returning” and “returned.”