Not producing oxygen, especially to describe certain forms of bacterial photosynthesis.
The term anoxygenic is most often used to describe the form of photosynthesis in purple bacteria, green sulfur bacteria, green non-sulfur bacteria, and heliobacteria. In this kind of photosynthesis, the electron flow is cyclic with all electrons used in photosynthesis eventually being transferred back to the single reaction center and oxygen is not produced.
Word origin: an– (without) + oxy(gen) + –ic.
See also: oxygen.