What is the correct spelling of the word formed by adding the suffix 'ness' to 'happy'?

The correct spelling of the word formed by adding the suffix 'ness' to 'happy' is "happiness." When creating a noun from the adjective "happy," the suffix 'ness' indicates a state or condition. In this case, it signifies the state of being happy. The base word 'happy' retains its original spelling, and the 'y' is replaced with 'i' before adding 'ness,' which is a common convention in English spelling when forming such nouns. Therefore, “happiness” is the accurate spelling that reflects this rule in English morphology, ensuring clarity and adherence to standard language conventions.