Regular Expression - Exclude list of words for a name

I'm trying to make a regular expression that accepts this:

• Only a-z, 0-9, _ chars, with a minimum length of 3
• admin, static, my and www are rejected.

For the first part, I already managed to do it with :

^[a-zA-Z0-9\\_]{3,}$

But I don't know how to exclude the words listed previously.

For example, that would mean :

• static is not allowed (of course), but
• statice is allowed
• estatic is allowed

Using this regular expression :

^(?!static|my|admin|www).*$

doesn't work well : it excludes statice (and everything after the unauthorized word).

Do you know which regular expression will fit my need?