dark matter—objects not directly detectable by astronomers, thought to exist in the universe to account for observed gravitational effects:
- The composition of dark matter is unknown, but may include new elementary particles.
gray matter—
1. brownish-gray nerve tissue, especially of the brain and spinal cord:
- The researchers found increased gray matter density in women in the left hemisphere of the brain associated with language.
2. mental power; intellect:
- The odious Krendler, in particular, learns to use his gray matter for, perhaps, the first time in his life.