This is not a new name... in the theory of algebraic data types there is a model of what it means to add and multiply types, resulting in "sum" and "product" types. I am not 100% sure but I believe these terms have been used since the early 70s.

The term "union" as used in C is highly related but not quite the same. If you add a tag to the union (and so have a "tagged union", often represented in C as a struct with an enum and a union) then you are equivalent in an information sense (but the usage is still different, as a C union says something very specific about how memory is used).

as mentioned elsewhere 'union' originally came from Algol68 where (eventually) they were implemented exactly as described in the article

It's not a new name, just one you're unfamiliar with.

Names are evil, abolish yourself of all naming and achieve true enlightenment!

Could you please stop posting unsubstantive comments to Hacker News?

https://news.ycombinator.com/newsguidelines.html

I wouldn't exactly call this unsubstantive... though maybe it was a bit aggressive towards the OP.