caveat / ˈkæviɑt /

Even though I have heard it quite a few times in the last months, this is one of these words that was not only completely new to me, but that I also find hard to get it right. I'm supposed to know by now the meaning, a warning to the reader, or something (e.g. a limitation) that needs to be considered because, though not necessarily bad, could be negative depending on the circumstances. So? Well, I understand it, somehow, but not so enough that I would be confortable using it.

Anyway, let's see some examples:
Engadget Podcast 262 - 10.28.2011 (time 16:25)

I would be shocked if Microsoft was throwing as much of its weitght behind this deal and it didn't get brought to the States. I'm sure that is a big caveat in their deal that they worked out, is that, you know, Nokia is finally in the try of really, really have a presence in the US

So this was one of those things that had to be considered.
New York Times: Calculating Poverty

A caveat: this data is not the same as what the Census Bureau will release on Monday, which among other things uses a different cost-of-living adjustment

 This is clearly a warning to the reader.

House of Japan: Sony Europe only PSP E-1000

It functions just like a regular PSP with one major caveat: it won’t have any WiFi connectivity

And this is kind of both.

In any case, whenever you hear the word 'caveat', be cautious.