A black cloud is a metaphor for a dark and ominous situation. The crossword solutions for the term BLACK CLOUD are OMEN (4 letters), GNATS (5 letters), GNAT (4 letters), NINE (4 letters), and NEBULA (6 letters). An OMEN is an event or occurrence that is seen as a sign of something to come. Gnats are small flying insects, and a GNAT is a single one of these insects. NINE is a number between eight and ten. A NEBULA is a large cloud of gas and dust in space, and a PALL is a dark cover or cloud.