The founding fathers set down a very specific definition of treason, partly because of a history of British monarchs beheading people with whom they were personally displeased for one reason or another on treason charges. Especially back when state, nation, and government were not well distinguished, nettling the king was easily treated as a capital crime.
Since adoption of the constitution, the legal, technical, operational definition of treason in the US has involved a (i) foreign (ii) enemy, and an enemy is a party with which we are at war. Not just competing for arms sales or disliking for human rights violations or even mutually rattling nuclear weapons: at war.
OK, it’s technically wrong to accuse Trump of treason, at least in the sense that he might face a sentence from a court for his behavior; James Risen has a deep dive into this question here. But we really need another word for what Trump is doing. I find it incontrovertibly evident, more than a year into the administration’s term, that Putin has a collar and leash on him and his calling a lot of shots. Trump’s inability to say a bad word, or even throw a teeny bit of shade at him, satisfy me as evidence of a financial chokehold, blackmail evidence of personal or financial behavior, or something else (or all of the above), and that he is basically a Putin stooge (whatever other revolting qualities he presents) fits comfortably with the news of Russian assistance to his election coming out today.
Is Russia an enemy? OK, maybe we need another word, but Putin doesn’t just want to sell more natural gas than we do, or even prevent Russians from listening to hip-hop: he wishes us ill, and the primary expression of this wish is that he has done everything he can to saddle us with a deliberately ignorant, racist, kleptocratic, mendacious, incompetent whose principal pleasures are being adulated and hurting the weak and unfortunate, and who has salted the government with liars, cheats, deliberate saboteurs like Pruitt and Devos, and completely incompetent bozos.
Some words have simultaneously a common, conversational but well-understood and serviceable, meaning and a specific, narrower, technical one in particular contexts. A vehicle is anything that rolls and carries people or stuff, including a riding lawnmower, but also a machine operating on the public ways and subject to traffic rules. My students can conspire to organize a surprise party for me, and conspiracy is also a sharply defined criminal offense. I’m ready to (i) recognize treason as acting affirmatively against the welfare of one’s country in cooperation with, or in the service of, foreign interests, and at the same time the particular crime delineated in the constitution, and (ii) to characterize the governance of the Trump administration as treasonous in the first sense. If anyone has another word for that, the comment section is open.
The English law of treason in 1775 was an incoherent mishmash of offences, including counterfeiting the Great Seal and supporting Jacobite claimants to the throne. But it was never just a cover for "beheading people with whom they [English kings] were personally displeased for one reason or another". This was just the propaganda of the American secessionists, part of the absurd claim that the constitutional monarch George III was a bloody Muscovite-style tyrant.
BTW, read historian Timothy Snyder's op-ed in the Guardian here. He argues that the USA has fought its first cyberwar with Russia, and lost. I'm convinced that a lot more still has to come out on Russian fixing of the Brexit vote. Cambridge Analytica sure looks like the FSB's willing or unwitting tool.
I was thinking a little further back, for example Henry VIII's execution of Ann Boleyn whose treason was not having a son.
Henry did not do this on a whim. A son was vital, as he saw it, to the continuance of the dynasty and the prevention of civil war. There wasn't any doubt that Boleyn's alleged adultery fell within the longstanding definition of treason. See the French king Philippe le Bel's appalling treatment of the lovers of his daughters in 1314. The evidence against Boleyn was thin and some of it (Smeaton's confession) extracted by torture or the threat of it.
Actively disloyal to America? Undermining our country to protect himself?
Betraying his promise to uphold, protect, and defend the Constitution?
Quisling comes to mind. As for the Russian indictments, there's no crimes there that look like anything that Americans would condemn their own government for doing in another country, which it has, regularly.
In a world where people who were against the trumped-up (ahem) invasion and occupation of Iraq were described as "objectively pro-Saddam", calling the action of trump and his cronies "treason" really doesn't seem a bridge too far (also ahem). "Quisling" and "puppet" also seem good, as does the perfectly adequate noun "traitor".
Meanwhile, insofar as trump's behavior has solidified the position of the dictator of north korea and improved that country's international standing, you have actions that do fall within the technical definition. (Albeit mens rea might be difficult)