The term "FNMA" stands for the Federal National Mortgage Association, commonly known as Fannie Mae. It is a noun and refers to a federally chartered corporation in the United States that plays an important role in the housing market by purchasing mortgages (loans used to buy homes) from lenders.
In summary, FNMA is an important player in the U.S. housing market, helping to make home purchases possible by buying mortgages from lenders.