What is a "Therapist"?

This question relates primarily to English language usage and not directly on legal regulation of professions, unless the bare word “therapist” is regulated in a material way to the question.

Colloquially, when I hear the word “therapist”, I think of someone like a clinical psychologist who provides mental health care or other social care. I’ve been thinking about other care disciplines that do not directly involve talking therapy or mental disorders, but are related to care nonetheless, and that include the term “therapy” in their names, such as chemotherapy. Is “chemotherapy” a form of “therapy”? Can a cancer doctor who practices chemotherapy legitimately refer to himself as a “therapist” without qualifying it?

E.g. :

Mary: “So, what do you do?”
John: “I’m a therapist.”
Mary “What kind, trauma, addiction, marital, occupational?”
John: “Chemo. I’m an MD who treats cancer, I don’t do talking therapy.”

I’ll just get a “The Rapist” joke out of the way now so everyone can get on with things.

I said “other”: Someone licensed by the state to be a “therapist”, of which there are several kinds:

Licensed Physical Therapist
Licensed Marriage and Family Therapist

and others as well.

Well, I suppose he could, but I have no idea why he’d wish to do so as this would be both confusing to others (most people would assume he’s involved in some sort of counseling or mental health care work) *and *make them think he has a job that is less well-respected by the public than the one he actually has.

FWIW I have never heard a physical therapist, massage therapist, etc., refer to him or herself as just a “therapist” even though the word is part of the name of their profession.

Some sort of head shrinker if there’s no modifier. If they’re a physical therapist, occupational therapist, speech therapist, massage therapist, etc., the adjective will be there. Other healthcare professionals tend to refer to some of them by initial: “Are we ordering OT? Did you call the PT yet?” and others the full title, “The speech therapist called. The massage therapist won’t be in next Tuesday.”

Who spends a lot of her professional time pushing paperwork ordering various _____Therapists, but not Therapists.

I am currently seeing both a social worker for talk therapy and a physical therapist for an injured shoulder. I refer to both of them as “my therapist”, which has lead to some confusion, even for me. For instance, I can’t just write “therapy appointment” on my calendar, I now have to specify. At one appointment with my talk therapist, I started telling her some stuff about “therapy”, and she was thoroughly confused until she realized that I wasn’t two-timing her with another social worker, I was just having physical therapy.

I was just thinking yesterday that now I have therapy for both mind and body.

My opinion as well.