Within certain variations of Gnosticism, especially those inspired by Monoimus, the Monad was the highest God which created lesser gods, or elements (similar to aeons). This view was according to Hippolytus inspired by the Pythagoreans, who called the first thing that came into existence the Monad, which begat the dyad, which begat the numbers, which begat the point, begatting lines, etc.
Gnostics were "people who knew", and their knowledge at once constituted them a superior class of beings, whose present and future status was essentially different from that of those who, for whatever reason, did not know.
The Gnostics, it is true, borrowed their terminology almost entirely from existing religions, but they only used it to illustrate their great idea of the essential evil of this present existence and the duty to escape it by the help of magic spells and a superhuman Saviour.
The Gnostics seem also to have used oil sacramentally for the healing of the sick, and even the dead were anointed by them to be rendered safe and invisible in their transit through the realms of the archons.
The monad begat the dyad, which begat the numbers, the numbers begat points, which begat lines, which begat two-dimensional entities, which begat three-dimensional entities, which begat bodies, which begat the four elementss earth, water, fire and air, from which the rest of our world is built up.
This way of putting it is misleading, however; monads do not interact with each other (are "windowless"), but rather are imbued at creation with all their future experiences in a system of pre-established harmony.
In pure functional programming languages such as Haskell, monads are data types that encapsulate the functional I/O-activity, in such a manner that the side-effects of IO are not allowed to spread out of the part of the program that is not functional (imperative).