Omicron Delta region was a region of space in the Milky Way Galaxy.
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.