Celery: Rib or stalk?

My mom wanted me to ask this: Is a celery “stalk” the bunch that you buy, with the twist-tie around it, while a “rib” is the individual stalk, like you put in a Bloody Mary?

I think the terms “rib” and “stalk” are interchangeable…but if so, then what do you call the whole bunch? A “head”?

A quick peruse of Google shows “stalk” used for both the whole thing and one rib – although I did find one site that said UK usage is “head” (whole thing) and “stick” (one rib). Personally, I try to use “head” or “bunch” for the whole thing and “stalk” for one unit. I’ve never used “rib,” although I recognize it as a legitimate term.

You know, this kinda reminds me of the ubiquitous story about the cook who didn’t know the difference between a head and a clove of garlic . . .

To me rib is reserved for meat, stalk is the term I would use for a single piece of celery and head i would use for the whole thing.