spread over vs flood

spread over is not a noun while flood is a noun.

Word	Noun	Adjective	Verb	Adverb
spread over	No	No	Yes	No
flood	Yes	No	Yes	No

As verbs, flood is a hyponym of spread over; that is, flood is a word with a more specific, narrower meaning than spread over:

spread over (noun)	flood (noun)
	the act of flooding; filling to overflowing
	a large flow
	light that is a source of artificial illumination having a broad beam; used in photography
	the occurrence of incoming water (between a low tide and the following high tide)
	the rising of a body of water and its overflowing onto normally dry land
	an overwhelming number or amount

spread over (verb)	flood (verb)
form a cover over	cover with liquid, usually water
	become filled to overflowing
	fill quickly beyond capacity; as with a liquid
	supply with an excess of