From the prefix yhdys- and vallat.

Yhdysvallat pl.

1. The United States (of America), the USA.

• When in a very official context, the full name of the country is Amerikan yhdysvallat – that omission is similar to the omission of "of America" in the English name.
• Unlike in other words in the same declension with Yhdysvallat, the genitive plural for this noun mostly used is the "old-fashioned" Yhdysvaltain, instead of Yhdysvaltojen. However, both of them are accepted, although the former is much more common.

• Amerikan yhdysvallat
• Amerikka
• Jenkkilä
• USA
• U.S.A.

• adjectives: yhdysvaltalainen