Dark matter traveling at ultra-relativistic velocities

Dark matter traveling at classical, non-relativistic speeds

Alternative spelling of oh dark thirty

plural of dark green fritillary

A big, bright orange and black butterfly with a greenish body, Argynnis aglaja, of the family Nymphalidae

(chiefly US military slang) An otherwise unspecified time of night; some time when it is dark out.

(chiefly US military slang) Half an hour past 12(am) midnight, or more formal and exact would be 00:30; The practice of adding “dark” and “thirty” (30) can be used sometimes as a slang term in place of an otherwise specific time a time of night, meaning some time when it is dark out between 00:01 - 05:00 hours local time.

(Catholicism) a period of time in which a holy person (someone believed to be potentially on their way to sainthood) experiences a seeming withdrawal of God's previously-felt presence in their lives, and undergoes stark spiritual attacks. This period of time is seen (by Catholics) to be a period in which God is calling the holy person to rid themselves of any remaining vestiges of self-pride and vanity that they may have.

(space science) A crater or other depression, on a solid, non-luminous celestial body, the interior of which contains one or more points which lie in perpetual shadow due to a combination of high latitude and being on a celestial body with low axial tilt.

plural of dark crimson underwing