Louis Sullivan was an American architect who revolutionized modernism through his skyscraper designs. Synonyms that can be used instead of architect Louis include designer, planner, and builder. The term "architect" specifically refers to a person who designs buildings and advises in their construction. "Designer" also works as it encompasses design elements beyond just architecture. "Planner" could be used as well, as it refers to someone who decides how a city or region should be developed, and architects are often integral to urban planning. Lastly, "builder" is a viable synonym for architect Louis, as they are involved in construction projects from beginning to end.