If there is a flood, a large amount of water covers an area which is usually dry, for example when a river flows over its banks or a pipe bursts.

If something such as a river or a burst pipe floods an area that is usually dry or if the area floods, it becomes covered with water.

If a river floods, it overflows, especially after very heavy rain.

If you say that a flood of people or things arrive somewhere, you are emphasizing that a very large number of them arrive there.

If you say that people or things flood into a place, you are emphasizing that they arrive there in large numbers.

If you flood a place with a particular type of thing, or if a particular type of thing floods a place, the place becomes full of so many of them that it cannot hold or deal with any more.

If an emotion, feeling, or thought floods you, you suddenly feel it very intensely. If feelings or memories flood back, you suddenly remember them very clearly.

If light floods a place or floods into it, it suddenly fills it.

If a river is in flood, it is flowing over its banks because it has more water in it than normal.

If you say that someone was in floods of tears or in a flood of tears, you are emphasizing that they were crying with great intensity because they were very upset.

If people, places, or things are flooded out, the water from a flood makes it impossible for people to stay in that place or to use that thing.