What does it mean to be self absorbed?

Someone said that I am self absorbed. What does that mean? Websters dictionary says that it means to be "absorbed in your own interests or thoughts", but other online dictionaries say that it means to be egotistical,selfish etc. Is a person that is introverted, thoughtful, or reflective self absorbed? Would a philosopher that spends a lot of time thinking and forming his theories about life be described as self absorbed? Isn't it good to think sometimes? Isn't everyone self absorbed to some degree?