to cover a place with water, or to become covered with water:
cover with water[intransitive and transitive]DN
Towns and cities all over the country have been flooded.
The houses down by the river flood quite regularly.
if a river floods, it is too full, and spreads water over the land around it:
river[intransitive and transitive]DN
There are now fears that the river could flood.
to arrive or go somewhere in large numbers [= pour, flow]:
go/arrive in large numbers[intransitive always + adverb/preposition]
Refugees are still flooding across the border.
Donations have been flooding in since we launched the appeal.
to send a very large number of things to a place or organization:
a plan to flood the country with forged banknotes
to receive so many letters, complaints, or inquiries that you cannot deal with them all easily:
We've been flooded with offers of help.
to produce and sell a very large number of one type of thing, so that the price goes down
flood the market with
Car manufacturers have been accused of flooding the market with cheap cars.
if light floods a place or floods into it, it makes it very light and bright
light[intransitive and transitive]
Light flooded into the kitchen.
flood something with something
The morning sun flooded the room with a gentle light.
if a feeling or memory floods over you or floods back, you feel or remember it very strongly
feeling[intransitive always + adverb/preposition, transitive]
I felt happiness and relief flooding over me.
Memories of my time in Paris flooded back.
if an engine floods or if you flood it, it has too much petrol in it, so that it will not start