The word lounge is commonly used in several languages. For example, in English and German, you may talk about a lounge at the airport or in a hotel. Despite its common use, you may soon realize (after reading this post) that quite a few people get the pronunciation wrong. Actually, this post is very much motivated by the fact that I was among this group!
The origin of this phenomenon seems to be two-fold. First, lounge is easily confused with the word launch. Whereas lounge is correctly pronounced as [laʊndʒ] (both in German and English, listen here), people often pronounce it like launch instead, namely as [lɔːntʃ] (listen here). However, the meaning of the associated verbs lounge and launch is very different. From the OLD, we have
to lounge: to stand, sit or lie in a lazy way
as opposed to
to launch: to make a product available to the public for the first time
Second, the spelling of lounge may suggest a French origin and hence a different pronunciation, especially for the letter g. However, lounge is proper English word.
With this knowledge, I’m sure you will feel a bit more relaxed the next time you are lounging in a lounge.