The suffix "-ful" is added to nouns to create adjectives that describe a quality or characteristic. For example, the word "joy" becomes "joyful," meaning full of joy. This suffix helps convey a sense of abundance or presence of the noun it modifies. When used, "-ful" often indicates a positive attribute. For instance, "thought" transforms into "thoughtful," suggesting someone who is considerate and caring. This suffix is commonly found in everyday language, enhancing descriptions and making them more expressive.