The word "兮兮" is formed through the reduplication of the character "兮", a classical Chinese particle used historically to denote a pause or exclamation. In modern usage, this reduplicated form functions as a suffix appended to adjectives or nouns, creating descriptive expressions that emphasize a particular state or manner, as seen in examples like "脏兮兮" (dirty) or "可怜兮兮" (pitiful).