What is the meaning of the word "professional"?

Definitions:

characteristic of or befitting a profession or one engaged in a profession adjective
- professional conduct
engaged in a profession or engaging in as a profession or means of livelihood adjective
- The professional trader possesses distinctive qualifications.
engaged in by members of a profession adjective
- professional occupations include medicine and the law and teaching
of or relating to a profession adjective
- we need professional advice
of or relating to or suitable as a profession adjective
- professional organizations