The salt water in or coming from the sea or ocean. (noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "seawater" in a sentence
"At Mac's Seafood, right on the beach, across from fishing boats still unloading their afternoon catch, we ate a dozen oysters from a paper plate, the liquor on the clams which is what you call the seawater pooling on top running over our chins."
"The Diablo Canyon power plant uses only seawater from the Pacific ocean."
"Is there enough glacial freshwater melting to actually, significantly change the amount of salt in seawater, which would mean the oceans (where they were affected) would freeze at a higher temp, among other effects?"