Omicron Delta region
The Omicron Delta region was a spatial region which was located somewhere in the Alpha or Beta Quadrant.
In 2267, the USS Enterprise discovered the Shore Leave Planet in this region of space. The starship returned to the region for some rest and relaxation in 2269. (TOS: "Shore Leave"; TAS: "Once Upon a Planet")
The novelization of "Once Upon a Planet" (as published in Star Trek Log 3) referred to this area as the "Omicron region," omitting the word "Delta" from its name.