I think the keyword "big data" ends up being used in even a lot of smaller cases, because everyone thinks what they have is "big data", I'm guessing because they do all genuinely have much more data than they might have a decade ago. But that still varies widely in size; what some companies think is "big data" is still perfectly analyzable, for non-realtime purposes, on one beefy workstation. Yet, because they'd never seen data with tens of millions of rows! before, and it breaks whatever system they were previously using to analyze stuff (SPSS, etc.), what they want to hire is a "big data" person.