origo

Origo, originis is third declension and feminine, which is worth flagging because the same -o, -inis shape gives masculines such as ordo and homo. It is built on orior, "to rise", so the sense is the point at which a thing rises: a river's source, a family's stock, the beginning of anything traceable.

Cato's history of Italy was called the Origines because it worked backwards to each city's founding, and the phrase ab origine, "from the beginning", is where "aboriginal" comes from. In this corpus the theological use is unavoidable: peccatum originale, original sin, the fault inherited at the origin rather than committed. English origin, original, originate and, at one remove, orient and abortion all sit on orior.