There are many synonyms for the phrase "high on." Some of the common ones include "intoxicated," "under the influence," "stoned," "drunk," "buzzed," and "euphoric." All of these terms refer to the state of being under the influence of drugs or alcohol, or experiencing intense emotions and feelings. Other synonyms for "high on" include "elated," "excited," "enthralled," "pleased," "thrilled," and "overjoyed." These words are often used to describe a sense of happiness and exhilaration that comes from a positive experience or achievement. Overall, there are many ways to describe the feeling of being "high on life" and the different emotions that come with it.