I understand it to be the transformation to ANY animal.
Yes, and werewolves fit into that category. Man beasts in TES are known as lycanthropes, and the name "Lycan" is simply an abbreviation (whether it was made famous in the movie Underworld or not.) If someone wants to call a werewolf a "Lycan" they have the right to do so, and they are not incorrect in calling them such. Also, Lycan is shorter than Lycanthrope or werewolf. If you don't like it, you have every right not to call them Lycans, but for the sake of a good joke, please don't crap on some guys humorous movie reference over it.