Definition of Oort cloud in English:
Oort cloud
proper noun
AstronomyA 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.
Pronunciation
Oort cloud
/ôrt kloud/ /ɔrt klaʊd/Are You Learning English? Here Are Our Top English Tips