The 'origin' of this custom/tradition is not known. = The 'origins' of this custom/tradition are not known. [=no one knows how this custom/tradition started]
He comes from 'humble origins'. [=he comes from a family that did not have high social status or much money]
The English word “rendezvous” is French 'in origin'. [=the English word comes from French]
(..) the pizzas are getting cold here! -Cutting Boulevard, huh? -Yeah, yeah. Which way? Now, you're sure this space freighter will return to its port of origin once it jettisons its food supply? And when we get there, we'll be able to find a way to transport you home. -Well, then, let's climb aboard. (..)1995 Toy Story