may we use "donaldduck" word in domain name? one of my client just register a domain from me, he use "donaldduck" word in domain name.

It all depends on how it's used, and if Disney owns a trademark on that phrase/name. From what I know of Disney, it wouldn't surprise me if they did, and would be opposed to it's being used.

I don't know for certain, but I would assume that Disney has trademarked that phrase.

It really depends on what you're doing with it. If you are selling donald duck t-shirts then yes Disney will probably come after you, and with good reason.

If you try to start donald duck web hosting company or something they will probably not notice. Not to say that they couldn't eventually still come after you..

That is such a famous trademark, that your client will probably have trouble if they use it for any kind of commercial activity.

go buy a duck, and some feed, name it Donald and place it in your backyard. :D

Yep, they can go after you if they wanted to. I had a domain once of a popular character and sure enough I got a letter from a law office representing the trademark owner. I had to give up the domain or face a lawsuit. I gave up the domain.

I do not think you would face any legal actions directly but your client would. I am pretty sure the name Donald Duck was trademarked. Do a search on google and I am sure you would know your answer.

http://en.wikipedia.org/wiki/Donald_Duck_in_comics

That link doesnt seem to point to any official trademark but maybe you could get the answer with a trademark search at your local office