Law is one of the key concepts in ancient Greek political thought. Two different legal-political terms were used for the concept of law in ancient Athens -although not simultaneously. Before putting an end to the tyranny of the Pisistratidae at the end of the sixth century, θεÏμÏÏ was used in the sense of state law whilst after the Cleisthenes democratic reforms at the beginning of the fifth century, νÏÎ¼Î¿Ï was the official legal-political term. This study reveals that such terminological change from θεÏμÏÏ to νÏÎ¼Î¿Ï reflects a profound change in Athenian political thought. Considering the fact that language mirrors thinking, this change in terminology may reflect a change in Athenian thinking. Hence, through philological analysis, this article aims to expound how ancient Greek political thought altered. Attempting to redefine the unit of Greek political life, ÏÏλιÏ, according to new meaning of the law, this paper is a contribution to the ancient Greek political philosophy.