- A large dark cloud charged with electricity and producing thunder and lightning; a cumulonimbus cloud.
- Something menacing or dreadful: thunderclouds of impending war.
- a large, dark cloud, usually a cumulonimbus, charged with electricity and producing thunder and lightning; a stormcloud
- (by extension) something menacing and brooding
- As the ominous thunderclouds of war gather over the Middle East, countries like France and Russia have threatened to use their veto in the United Nations to thwart immediate U.S. military force against Iraq. -