A particular point with respect to which positions are measured. For example, positions on the Earth are frequently measured relative to the point on the Equator which is due South of Greenwich, England. In GPS coordinates, that point is given as 0,0 (its latitude is 0, and its longitude is 0). Or we might say something like “10 miles southeast of town hall.” In that case, town hall would be the origin.
Come, you lost Atoms, to your Centre draw,
And be the Eternal Mirror that you saw:
Rays that have wander'd into Darkness wide,
Return and back into your Sun subside.
From Farid al-Din Attar's
The Conference of the Birds