dark matter

dark matter

noun

Definition of DARK MATTER

:  nonluminous matter not yet directly detected by astronomers that is hypothesized to exist to account for various observed gravitational effects

First Known Use of DARK MATTER

1982

Rhymes with DARK MATTER

back matter, backscatter, bespatter, flat-hatter, front matter, gray matter, no matter, standpatter, the matter, white matter, wildcatter

dark matter

noun    (Concise Encyclopedia)

Nonluminous matter not directly detectable by astronomers, hypothesized to exist because the mass of the visible matter in the universe cannot account for observed gravitational effects. Dark matter comes in two varieties: baryonic, which is about 5 percent of the universe, and nonbaryonic, which is 22 percent of the universe. The nonbaryonic dark matter is believed to consist of heavy, electromagnetically neutral particles called weakly interacting massive particles (WIMPs).