This. Some of the advice only works out of context, for example:
> What's an appointment_list? A calendar
No. Chances are that "appointment" is already a thing in your domain language -- the language you'd use to talk to your customers and stakeholders -- and so appointment_list is a much clearer name than calendar, as long as we make the reasonable assumption that it names a collection of appointments.
None of the examples of just using a single word seemed like improvements to me. appointment_list to calendar was by far the worst—calendar can mean a lot of things, and a list of appointments was not even the first thing that comes to mind for me—but in all of the cases the single word meant something significantly different than the thing it was replacing.
> What's an appointment_list? A calendar
No. Chances are that "appointment" is already a thing in your domain language -- the language you'd use to talk to your customers and stakeholders -- and so appointment_list is a much clearer name than calendar, as long as we make the reasonable assumption that it names a collection of appointments.