What is a professional?

For a denotative meaning:

1. Expert and specialized knowledge in field which one is practising professionally. 

2. Excellent manual/practical and literary skills in relation to profession.

For my own idea, being professional can be described as a person which is well-oriented or well-educated on what is he/she doing. He/she can easily answer questions regarding to his/her work. You can easily trust him/her any task that is related to his/her profession. :D