Kurios is a Greek word that may apply to God

God

God is the English name given to a singular being in theistic and deistic religions who is either the sole deity in monotheism, or a single deity in polytheism....

, lord

Lord

Lord is a title with various meanings. It can denote a prince or a feudal superior . The title today is mostly used in connection with the peerage of the United Kingdom or its predecessor countries, although some users of the title do not themselves hold peerages, and use it 'by courtesy'...

, master, or guardian. In ancient Greece

Ancient Greece

Ancient Greece is a civilization belonging to a period of Greek history that lasted from the Archaic period of the 8th to 6th centuries BC to the end of antiquity. Immediately following this period was the beginning of the Early Middle Ages and the Byzantine era. Included in Ancient Greece is the...

, a woman could not enter into a contract herself and arrangements were made by her guardian or Kurios. For an unmarried woman the Kurios would be her father, and if dead, brothers an uncle or relative would be the Kurios.

In some cases, when reading the Hebrew Bible

Hebrew Bible

The Hebrew Bible is a term used by biblical scholars outside of Judaism to refer to the Tanakh , a canonical collection of Jewish texts, and the common textual antecedent of the several canonical editions of the Christian Old Testament...

 the Jews would substitute Adonai (my Lord) for the Tetragrammaton

Tetragrammaton

The term Tetragrammaton refers to the name of the God of Israel YHWH used in the Hebrew Bible.-Hebrew Bible:...

 (the written representation of the Name of God), and they may have also substituted Kurios when reading to a Greek audience (as in the Septuagint translation). Origen

Origen

Origen , or Origen Adamantius, 184/5–253/4, was an early Christian Alexandrian scholar and theologian, and one of the most distinguished writers of the early Church. As early as the fourth century, his orthodoxy was suspect, in part because he believed in the pre-existence of souls...

 refers to both practices in his commentary on Psalms (2.2). The practice was due to the desire not to overuse the name of God. Examples of this can be seen in Philo

Philo

Philo , known also as Philo of Alexandria , Philo Judaeus, Philo Judaeus of Alexandria, Yedidia, "Philon", and Philo the Jew, was a Hellenistic Jewish Biblical philosopher born in Alexandria....

. In The Jewish War (7.10.1) Josephus

Josephus

Titus Flavius Josephus , also called Joseph ben Matityahu , was a 1st-century Romano-Jewish historian and hagiographer of priestly and royal ancestry who recorded Jewish history, with special emphasis on the 1st century AD and the First Jewish–Roman War, which resulted in the Destruction of...

remarked that Greek speaking Jews refused to call the emperor Kurios for they reserved that word for God.