Cloudy means filled with clouds or unclear, like when gray clouds cover the sky and hide the sun. On a cloudy day, you might not see blue sky at all, just layers of white or gray clouds stretched across the horizon. Meteorologists describe weather as cloudy when clouds cover most or all of the sky.

The word also describes anything that's not clear or transparent. Cloudy water in an aquarium means you can't see through it easily, perhaps because of dirt, algae, or stirred-up sand. When you breathe on a cold window, your breath makes the glass cloudy for a moment. A cloudy gemstone lacks the crystal clarity of a clear one.

Cloudy can describe thinking too. When someone's memory of an event is cloudy, they can't quite remember the details clearly. If a person's judgment seems cloudy, they might be confused, tired, or distracted, making it hard for them to think straight. Scientists or detectives want clear evidence, not cloudy reasoning that might lead to wrong conclusions.

The opposite of cloudy is clear: clear skies, clear water, clear thinking. But cloudy isn't always bad. Cloudy days can be perfect for photography because the clouds soften harsh sunlight, and sometimes cloudy lemonade tastes better than the completely clear kind.