Culture is hard to define, which is probably why most of the people who use the word don't even try.
It's one of those cross-discipline buzzwords or phrases — like synergy, best practices, new normal or deep dive — that mean so little it can be used anywhere and be applied to anything. It's the beige paint of the English language. In isolation it's hard to notice; made ubiquitous, it's as annoying as Mozart dumbed down to Muzak.
Like art and fraud, you know culture when you see it, and we saw it in action over the last two weeks with the Minnesota Vikings.