"Doctor's appointment" or "doctors appointment"?

I've looked this up online, but I can't find any explanations from reasonably credible sources, so I'm posting my question here! (Was that a comma splice?)

Should I refer to the appointment that I made with my doctor as a "doctor's appointment" or "doctors appointment"? What if I'm referring to more than one appointment with two different doctors?

Solution 1:

As the doctor also has an appointment with you, doctor's appointment is appropriate in its own right. It is also by far the most common as a set phrase:

Any other plural usage would be entirely subjective.

Graph source: Google Books Ngram

Solution 2:

You can use either doctor appointment or doctor's appointment. Merriam-Webster indirectly supports the latter with its second example under its listing for appointment.

I agree with tchrist that the word doctor in doctor appointment is a noun (attributive noun I believe), although the definition of an attributive noun is a noun used as an adjective, so maybe it's just semantics at some point.

To the point above about the appointment being reciprocal, I can sort of get on board with that. I suppose the doctor does have an appointment with the patient as well, but I think the emphasis is a bit off in that perspective because I think the ownership pertains more directly to the patient (just my take).

In any case, you should be okay with either usage above.