There's also a term for once a day but I've forgotten it.

Why can't they just say DAILY?

And is there a reason they HAVE to use Latin instead of plain ole English. It's not as if they have that many more syllables to deal with. Not only that, they aren’t even using the entire words, just abbreviations. I can understand using Latin in some circumstances, when you don’t want to alarm a patient before a doctor has had a chance to explain the situation for example, but why do they do it in this case?