What does 물경 (勿驚) mean?

勿 (물) can mean either Do not or without, and 경 (驚) means surprise or surprised, so it seems 물경 could mean either Do not be surprised or without surprise. However, according to my Korean-English dictionary, 물경 translates as surprisingly (enough) or It will surprise you (but), which somewhat confusingly suggests that 물경 should be translated as Don't be surprised. In fact, my Korean-Korean dictionary explains it more clearly:

[놀라지 말라는 뜻으로] 엄청난 것을 말할 때 앞세워 이르는 말.

[With the meaning of "Don't be surprised"], it is said before saying something that is surprising or absurd.

Even though it literally translates as "Don't be surprised, [but]," the adverb "surprisingly" seems to be a better translation these days. Here is the example sentence from my Korean-English dictionary:

쌓인 빚이 물경 100만 원이었다.

The debt went on increasing, reaching at last a surprising amount of one million won. 

I am not sure how often 물경 is used these days, but, instead, I use the adverb 놀랍게도, which seems to be the pure Korean substitute.