who can give me some definitions about hackers

Here you'll find links to quite a few definitions of "hacker":

http://onelook.com/?w=hacker&ls=a

the term hacker is a word that has chaged radically with the times.
(like the word marriage from the foundation of america - 2004, and the
politically correct word that it is today)

I was going to sit down and respond to this question.  But I needed a
piece of information clarified, and found a great responce.
http://en.wikipedia.org/wiki/Hacker

has all the definition you could ever want.

Hacker originally referred to a clever or expert computer programmer.
These days it is more used to refer to someone who can gain
unauthorized access to other computers/networks or data. A hacker can
find or "hack" his or her way through the security levels of a
computer system or network. This can be as simple as figuring out
somebody else's password or as complex as writing a custom program to
break another computer's security software.

Hackers cause software manufacturers release periodic "security
updates" to their programs. While it is unlikely that the average
person will get "hacked," some large businesses and organizations
receive multiple hacking attempts a day.

Hi darkbeast,

I answered a question which might be of interest to you:
http://answers.google.com/answers/threadview?id=254831


Best regards,
tlspiegel