It's not "lebendig", however vivid and lucid have a very similar meaning just as in English. That's what I was trying to say haha So it's easy to be confused if English isn't your first language.

"bewusst" could be used as lucid, however I would translate "bewusst" as conscious or aware. "bewusst" has more this awareness-touch to it whereas "lucid" in German just describes a sensation of obviousness, clearness,... Ohhh that's actually quite hard to describe...

So to sum up my german translation for "lucid" would be "klar" or "deutlich". I think "klar" suits... considering that the situation of being in a dream is "klar/ clear" for you (you know about it)