British : a thousand milllions
This is from Merriam-Webster. What I find particularly curious is that it is not on the Cambridge site. And I've never seen it used.
Is that actually used in the UK instead of billion? I was sure the answer was "no", but I've learned not to speak too quickly.
The topic of "what is a billion?" raises a lot of discussion among those who do not routinely use the term.
This is a very long thread and contains a great deal of opinion.
Below I have quoted some of the posts that contain straightforward and robust statements about the UK use of billion.
You are welcome to read the rest of the thread and to add to the discussion if you wish.