stealing

You are opening a can of worms on this one.
I'd say its pirating. If you take the CD without asking would be stealing.

 

It is copyright infringement, some people care about that, others don't...

Stealing is a term that others will dispute.

 

I won't. Stealing of this type is by definition the crime of embezzlement, which involves taking something that isn't yours. The library allows you to listen to the CD for the time that it's in your possession, not to keep its contents beyond that set time. So, the OP's question is easily answered: it is indeed "stealing" in the pejorative sense.