when to pronounce s

How could the s at the end of Un nounours is pronouced. 

When do we pronouce the s and when do we not? 

Thank you

Good question. Generally, the 's' is silent in French, but un ours (a bear) is an exception, so un nounours (a teddy bear) follows the exception. Unfortunately, I don't think there are any hard and fast rules on the exceptions (other than pronouncing the 's' on foreign-derived words), they just need to be learned.

Here are a couple good answers, but Torusan is right. And I would say, just use a dictionary.

Link: http://french.stackexchange.com/questions/2706/when-to-pronounce-s-at-the-end-of-words

Link: http://french.stackexchange.com/questions/2826/unpredictable-pronunciations

The second link has a reference to an old book and the words are there:

Link: http://books.google.com.au/books?id=P8oDAAAAQAAJ&printsec=frontcover#v=onepage&q=ours&f=false

I found this little site also with audio pronunciations like here at Rocket Languages:

Link: http://www.languageguide.org/french/grammar/pronunciation/final_consonants.html

Fun isn't it? Like Disney: http://en.wikipedia.org/wiki/Supercalifragilisticexpialidocious