Theodorus

Theodorus is a Greek male given name meaning “gift of God,” from the elements theos (god) and doron (gift). It has appeared in various forms across Greek, Latin, and modern usage, notably as Theodoros in Greek.

The most prominent bearer is Theodorus of Cyrene (circa 515–430 BCE), a Greek mathematician from Cyrene in North Africa. He is associated with early work on irrational numbers and with a geometric construction known as the Theodorus spiral, which builds a sequence of right triangles whose hypotenuses correspond to square roots: sqrt(2), sqrt(3), sqrt(4), and so on. Ancient sources attribute to him ideas about the irrationality of certain square roots, though the exact demonstrations are not securely documented and details vary among scholars. His writings, if they existed in full, would place him among the pre-Euclidean mathematical tradition in Greece.

Beyond mathematics, Theodorus appears in Christian and Byzantine contexts as a given name and is borne by several saints and church figures over the centuries. In modern times, Theodorus (or Theodoros in Greek) remains a common given name in Greek-speaking communities and among people of Greek heritage, with various individuals known in religion, scholarship, and the arts.

In summary, Theodorus denotes both a classical Greek given name and, most notably, a 5th-century BCE mathematician associated with early irrational-number concepts and the geometric Theodorus spiral, while also serving as a historical and religious name with continued use in subsequent eras.