That is literally what the grandparent poster said, and matches the first two definitions I can find on Google.
Personally, I often think of this example: https://news.ycombinator.com/item?id=3033446
It's really interesting to see how both sides approach the problem (without rushing it), but only one of them solves it. That certainly counts as a 10x difference?
> "10x engineer" is a marketing gimmick used to gain leverage in various ways, IMO.
I've been following the discussion, and I think that "10x is a lie" has itself become a dangerous meme. It's already hard to tell some of my clients that developer quality matters, that hiring cheap developers en masse is pointless if they can't reliably fizzbuzz. Now Developer Twitter decides to proudly proclaim that everyone is equally capable as a developer, except some of them are toxic jerks. Sigh.