Poleis, the ancient Greek word for city-states, can be defined as independent communities consisting of a city and the surrounding countryside. The word "poleis" has several synonyms, including "polis," "city-state," and "city republic." When ancient Greeks used the word poleis, they referred to their own city-states, such as Athens, Sparta, and Thebes. Today, scholars use the term to describe the political organization of ancient Greece. The word poleis has influenced the modern English language, with the word "metropolis" being derived from the Greek "meter polis," meaning "mother city." The concept of a city-state remains relevant to modern-day politics and international relations.