原文：
For various reasons related to our WordPress trademark, we ask if you're going to start a site about WordPress or related to it that you not use "WordPress" in the domain name. Try using "wp" instead, or another variation. We're not lawyers, but very good ones tell us we have to do this to preserve our trademark. Also many users have told us they find it confusing.
If you already have a domain with "WordPress" in it, redirecting it to the "wp" equivilent is fine, just as long as the main one users see and you promote doesn't contain "WordPress."
"WordPress" in sub-domains is fine, like wordpress.example.com, we're just concerned about top-level domains.
We've told this to anyone who has ever asked us, we just wanted to make it public so more people could be aware of this policy.
原文地址：
http://wordpress.org/about/domains/
主要意思：
1.为了保护wordpress这个商标，如果你做的是和wordpress相关的网站，请不要在域名中包含wordpress，可以用wp代替。
2.子域名不受限制，你可以使用类似
http://wordpress.zzbaike.com 这样的域名
