Definition of Oort cloud in English:

Oort cloud

Pronunciation /ôrt kloud/ /ɔrt klaʊd/

proper noun

Astronomy
  • A spherical cloud of small rocky and icy bodies postulated to orbit the sun beyond the orbit of Pluto and up to 1.5 light years from the sun, and to be the source of comets. Its existence was proposed by J. H. Oort.