Is lonelieness a sign of depression?

Yes, it can be a sign o depression, but come with other sign like Sadness or Sad recollections, Pessimistic attitude, Few physical activity, insomnia, change in the nutritional habits and other.

But only a doctor can determine if it is a question of depression, and if it is something serious.

The depression cannot be surpassed by will force only(maybe but will be so hard), also they are needed some medicines for the nerves and that help to improve the state of the patient (prozac in difficult cases)

Nevertheless, to much people it likes to be alone because them aid to concentrate itself better in its profession or some problem in individualnot for me
yes - if there are people in your environment and you still feel lonely......
Excessive loneliness feelings when your around other people can be a sign of depression.

I never feel lonely , even when I was living in the very deep countryside by myself.
Actually , I loved it.
Withdrawal, and isolation is. See depression treatments, at http://www.ezy-build.net.nz/~shaneris... on page 2.
Loneliness can be the cause of depression. I would talk to a doctor.