(meteorology) A tapering cloud descending from a larger storm cloud, indicating the presence of an intense vortex. A tornado is a funnel cloud which reaches the ground.

A large cloud of smoke, flame and debris that rises into the sky as a result of a large explosion, especially after a nuclear explosion, characterized by a long shaft rising from the ground into a much-larger or more-spread-out top, reminiscent of a mushroom in shape.

(idiomatic) Often in the phrase on cloud nine: a state of bliss, elation or happiness. / (idiomatic, possibly nonstandard) A state of fantastic or impractical dreaming or thinking.

(astronomy) The Solar System's Oort cloud, extending from 50,000 to 100,000 astronomical units (approximately 1 light year) from the sun; supposedly the source of most comets around the Solar System.

A series of points in three-dimensional space that collectively describe the geometry of a physical object.

(idiomatic) Whose future is uncertain due to an anticipated threat or change in circumstance. / (idiomatic) Under suspicion; subject to critical inspection.

(astronomy) A large and relatively dense cloud of cold gas and dust in interstellar space from which new stars are formed

(property law) An encumbrance or claim on a title (ownership) to real property sufficient to interfere with title transfer until the problem has been resolved.

(astronomy) Either of two irregular galaxies that are close companions of our Milky Way galaxy.

(idiomatic) In a state of elation; very happy; blissful.