What is the meaning of the word "waikiki"?

Definitions:

A famous beachfront neighborhood in Honolulu, located on the island of Oahu in Hawaii, well known for its stunning beaches, luxury hotels, and vibrant nightlife. NOUN
- They spent their vacation in Waikiki, enjoying the pristine beach and exploring the local attractions.
A neighborhood in Honolulu, known for its beach, which is a major tourist destination, and famous for its historical significance as surfing hub and for its iconic view of the Diamond Head crater. NOUN
- Surfing lessons in Waikiki are popular among visitors eager to experience Hawaii's famous waves.