Classical Mythology . a shining cloud sometimes surrounding a deity when on earth.

a cloud, aura, atmosphere, etc., surrounding a person or thing

The candidate was encompassed with a nimbus of fame.

halo ( def. 1 ) .

the type of dense clouds or cloud mass with ragged edges, that yields rain or snow; a rain cloud.

( initial capital letter ) U.S. Aerospace . one of a series of polar-orbiting meteorological and environmental research satellites, the last of which Nimbus 7, launched 1978, was the first satellite designed to monitor atmospheric pollutants.