text: An expansive vocabulary can simplify communication, not make it more complicated as most people might infer. It allows people to say what they mean with greater precision. Yak Tack helps people expand their vocabulary. How Yak Tack Works Type a word you'd like to remember. Or, email firstname.lastname@example.org with the word as the subject. Get an email with the definition at expanding daily intervals. This is known as spaced repetition. During the first few intervals, simply read the email and delete it. With later intervals the email will ask you to pick the right definition. We stop at interval 13. After each interval, the word will be easier to recall when you hear or read it again.