There are numerous words that can be used as synonyms for the phrase "feel happy". Some of the most commonly used ones include joyous, delighted, elated, thrilled, content, gratified, glad, overjoyed, gleeful, and ecstatic. Each one of these words represents a slightly different degree or level of happiness, with some being more intense than others. For example, "ecstatic" describes a feeling of extreme happiness that is almost overwhelming, while "glad" is a more mild and relaxed expression of happiness. Regardless of which word is used, all of these synonyms accurately convey a sense of pleasure, joy, and positivity.