I posted a few weeks ago discussing the concept of when big data really matters. I said, and I'll repeat. Big Data is big when it provides big (meaningful) insights that can then be used to drive business decisions and ultimately business value. I'm speaking of "business" in very broad terms here. Not just standard corporate business.

So, in my opinion, Big Data is much more than just data measured by velocity, variety, and volume. These are relevant and will impact your technology choices.

If you can ask and then answer big / important questions with data then it's a big no matter the volume, velocity, and variety.