cloud

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A visible body of very fine water droplets or ice particles suspended in the atmosphere at altitudes ranging up to several miles above sea level.
• noun A mass of particles or droplets, as of dust, smoke, or steam, suspended in the atmosphere or existing in outer space.
• noun A large moving body of things in the air or on the ground; a swarm.
• noun A collection of particles or other small entities.
• noun An opaque mass of particles suspended in water.
• noun A dark region or blemish, as on a polished stone.
• noun A state or cause of sadness, worry, or anger.
• noun A state or cause of confusion or misunderstanding.
• noun A state or cause of suspicion or disgrace.
• noun A large area of coordinated wireless Internet service.
• noun The collection of data and services available through the Internet.
• intransitive verb To cover or obscure with clouds.
• intransitive verb To darken, obscure, or make less transparent.
• intransitive verb To make sorrowful, troubled, or angry.
• intransitive verb To cause to appear sorrowful, troubled, or angry.
• intransitive verb To make difficult to know or understand; make obscure or uncertain.
• intransitive verb To confuse.
• intransitive verb To cast aspersions on; sully.
• intransitive verb To become cloudy or overcast.
• intransitive verb To become dark, obscure, or less transparent.
• intransitive verb To show sorrow, worry, or anger.
• idiom (in the clouds) Impractical.
• idiom (under a cloud) Under suspicion or in a state of disgrace.

from The Century Dictionary.

• noun Feussner's method, which consists in observing the location on the map of the shadow of a cloud and at the same time observing the altitude of the sun. The formulæ needed for calculation are given in Abbe's “Meteorological Apparatus and Methods” (1887).
• noun The kinematic method (employed in connection with Abbe's marine nephoscope), in which observations give two zenithal apparent movements of the cloud for two corresponding known movements of the observer on a boat or wagon: eight quantities, that is directions and rates of motion, are thus known which are introduced into the analytical trigonometrical equation, and the true altitude and motion of the cloud are found by elimination.
• noun Lambert's method, which consists in observing the velocity of the shadow of the cloud on the ground and also the apparent angular velocity of the cloud at the zenith, whence the altitude or distance is calculated by trigonometrical formulæ.
• noun Trigonometric methods, which involve the use of the cloud-theodolite, photogrammeter, or cloud-camera.
• noun Espy's dew-point method of determining the altitude of the base of a cloud, which assumes that the altitude of the base is equal to the depression of the dew-point expressed in centigrade degrees multiplied by 100 meters or expressed in degrees Fahrenheit multiplied by 186 feet.
• noun A rock; a hill.
• To overspread with a cloud or clouds: as, the sky is clouded.
• Hence To cover as if with clouds: in various figurative applications, as to obscure, darken, render gloomy or sullen, etc.: said of aspect or mood.
• To variegate with spots or waves of a darker color appearing as if laid on over a lighter, or the reverse: as, to cloud a panel; a clouded sky in a picture.
• To place under a cloud, as of misfortune, disgrace, etc.; sully; tarnish: as, his character was clouded with suspicion.
• To grow cloudy; become obscured with clouds: sometimes with up.
• noun A collection of visible vapor or watery particles suspended in the air at a considerable altitude.
• noun A semblance of a cloud, or something spread out like or having some effect of a cloud: commonly followed by a specification: as, a cloud of dust; a ship under a cloud of canvas (that is, a large spread of sails).
• noun A clouded appearance; a dark area of color over a lighter material, or the reverse, as bloom upon a varnished surface.
• noun In zoology, an illdefined, obscure, or indistinct spot or mark, often a spot produced by the internal structure seen through a semi-transparent surface.
• noun Anything that obscures, darkens, threatens, or the like.
• noun A multitude; a collection; a throng.
• noun A woman's head-wrap made of loosely knit wool.
• noun Absorbed in day-dreams; visionary; absent-minded; abstracted.