1. A description of those parts of the ocean that are not reached by sunlight, or plants that grow there without synthesizing light: The remote controlled camera was able to explore the aphotic depths of the ocean, looking for rare life forms.
2. A reference to any environment or habitat that has no sunlight of any biological significant intensity: The fish that lived for a long time in the dark cave evolved into a state of blindness because of their aphotic environment.
3. Etymology: from Greek a-, "not, without" + phos, "light"; literally, "no light".