1. a person who cherishes or pursues high or noble principles, purposes, goals, etc. Synonyms: optimist, perfectionist, reformer, visionary, utopianist. Antonyms: pragmatist, skeptic, cynic.
2. a visionary or impractical person. Synonyms: romantic, romanticist, dreamer, stargazer. Antonyms: realist, materialist.
3. a person who represents things as they might or should be rather than as they are: My friend is an idealist, who somehow thinks that we always agree.
4. a writer or artist who treats subjects imaginatively.
5. a person who accepts the doctrines of philosophical idealism, as by representing things in an ideal form, or as they might or should be rather than as they are.