noun
dark matter
Astronomical term for non-luminous matter inferred from gravitational effects.
宇宙の質量の大部分は暗黒物質だと考えられている。
Most of the mass in the universe is thought to be dark matter.
暗黒エネルギー is dark energy, a different concept from dark matter, responsible for the accelerating expansion of the universe.
Compound of 暗黒 (darkness) and 物質 (matter), a calque of English 'dark matter'.