Overview
The term monad comes from the Greek feminine noun monas (nominative singular, μονάς), "one unit," where the ending -s in the nominative form resolves to the ending -d in declension.
In some gnostic systems the Supreme Being is known as the Monad, the One, The Absolute Aiōn teleos (The Perfect Æon, αἰών τέλεος), Bythos (Depth or Profundity, Βυθός), Proarchē (Before the Beginning, προαρχή), and Hē Archē (The Beginning, ἡ ἀρχή) and The ineffable parent. The One is the high source of the pleroma, the region of light. The various emanations of The One are called æons.
According to Theodoret's book on heresies (Haereticarum Fabularum Compendium i.18) the Arab Christian Monoimus (150-210) used the term Monad to mean the highest god which created lesser gods, or elements (similar to æons). In some versions of Christian gnosticism, especially those deriving from Valentinius, a lesser deity known as the Demiurge had a role in the creation of the material world in addition to the role of the Monad. In these forms of gnosticism, the God of the Old Testament is often considered to have been the Demiurge, not the Monad, or sometimes different passages are interpreted as referring to each.
This Monad is the spiritual source of everything which emanates the pleroma, and could be contrasted to the darkness of pure matter.
Read more about this topic: Monad (Gnosticism)