Fog at a distance from the earth
Types of clouds include: cirrus, cumulus, stratus, nimbus, cirrocumulus, cirrostratus, altostratus, altocumulus, cumulonimbus, stratocumulus, nimbostratus; woolpack*, scud*, meteor*, curl-cloud*, mare's tail*, colt's tail*, cat's tail*, mackerel sky*, thunderhead*, sheep*.
Any nebulous mass
A very large number of things grouped together:army, crowd, drove, flock, horde, host, legion, mass, mob, multitude, ruck1, score (used in plural), swarm, throng. See big, group verb
To make dim or indistinct:becloud, bedim, befog, blear, blur, dim, dull, eclipse, fog, gloom, mist, obfuscate, obscure, overcast, overshadow, shadow. See clear
To contaminate the reputation of:befoul, besmear, besmirch, bespatter, blacken, denigrate, dirty, smear, smudge, smut, soil, spatter, stain, sully, taint, tarnish. Idioms: give a black eye to, sling (or throw) mud on. See attack, clean