1. Unswerving in allegiance.
  2. Faithful in allegiance to one’s lawful sovereign or government.
  3. Faithful to a private person to whom faithfulness is due.
  4. Faithful to a cause, ideal, custom, institution, or product.
  5. Showing loyalty.

The emotion of Loyal is found in the Kidney meridian in the Water element.

Definition from Dictionary by Merriam-Webster.