General English

General Science

  • noun a circle of light seen round the Sun or Moon, caused by ice crystals in Earth’s atmosphere


  • prefix
    (written as halo-)


  • In a galaxy, the volume of space above and below the plane of its main structure. The halo contains old stars and globular clusters as well as gas clouds consisting mainly of neutral hydrogen. The halo contains a far lower density of matter than the main body of the galaxy, which is crammed with stars and other material.
  • Atmospheric phenomenon consisting of a circular ring of light around the Sun, caused by refraction of sunlight by ice crystals high in the Earth’s atmosphere. These crystals can also form a faint second image of the Sun.


  • On the screen of a CRT, such as that of a TV, an unwanted light or dark zone which surrounds an image, especially bright spots.
  • synonymhalation


  • noun
    (written as HALO)
    a covert method of deploying troops by parachute, in which the aircraft flies at a very high altitude in order to avoid detection, and the parachutists then descend a considerable distance through the air before opening their parachutes.
  • acronym forhigh altitude low opening
    (written as HALO)


  • noun a photographic effect seen as a dark region with a very bright line around it, caused by pointing the camera into the light
  • noun thicker ink at the edge of halftone dots, which makes the dots darker