To hearken means to listen carefully and pay close attention, especially with the intention of following what you hear. When a knight in an old story hearkens to his king's command, he listens with respect and prepares to obey.

The word sounds formal or old-fashioned today. You'll rarely hear someone say “Hearken to my words!” in everyday conversation, though you might encounter it in historical novels, fantasy stories, or old texts like the King James Bible. Characters in medieval settings often hearken to proclamations or warnings.

In modern English, we usually say “listen” or “pay attention” instead. But hearken carries extra weight: it suggests truly listening with your mind and heart, ready to understand and respond. When someone says “hearken back to an earlier time,” they mean to remember or refer back to it, like when a teacher says, “This lesson hearkens back to what we learned about fractions last month.”