dark light · noun1
Blend of dark matter + light. From being a force found in the dark sector that acts on dark matter, analog to light in the "light sector" (the part of the universe that is not part of the dark sector) that acts on "light matter" (ordinary matter that interacts electromagnetically, thus visibly).
dark light · noun2
From dark + light; dark being like black, "dark" being a metaphor for the invisible (non-visible light).
Etymology from Wiktionary, CC BY-SA 4.0.