Within the text of HTML versions of articles in APA PsycArticles you will notice that some words have a dotted line under them. If you click one of these words, you will see the definition (from the APA Dictionary of Psychology).
You can turn the definitions off by clicking “Turn Dictionary Off” command in the menu bar at the top of the screen.
To turn the dictionary back on, click “Turn Dictionary On” in the menu bar at the top of the screen.