In the U.S. Constitution, Article 3 Section 3 reads:
Treason against the United States, shall consist only in levying War against them, or in adhering to their Enemies, giving them Aid and Comfort. No Person shall be convicted of Treason unless on the Testimony of two Witnesses to the same overt Act, or on Confession in open Court.
and in federal law treason is defined as:
The offense of attempting to overthrow the government of one's country or of assisting its enemies in war; specifically: the act of levying war against the United States or adhering to or giving aid and comfort to its enemies by one who owes it allegiance.
This statement explicitly limits the allowable definition of treason to be very very narrow, due to overuse of "treason" by the English. Importantly, you have to either go to war against the U.S. or aid enemies, not "merely" aid another state or act against the interests of the U.S.
Therefore, there is a distinction between acts that would be reasonably described as treasonous based on a dictionary definition (for example "the betrayal of a trust") and those that are legally treason according to the U.S. Constitution. Merriam-Webster has a whole article on the use of the term in the U.S. context.
Only one person has been tried, convicted, and executed for treason in the U.S. since the Constitution was ratified.