professional2 W3 [countable]
someone who earns money by doing a job, sport, or activity that many other people do just for fun [↪ amateur]:
Hurd signed as a professional in 1998.
top snooker professionals
someone who works in a job that needs special education and training, such as a doctor, lawyer, or architect:
health professionals (=doctors, nurses etc)
someone who has a lot of experience and does something very skillfully:
You sing like a real professional.
someone who is very good at a sport and is employed by a private club to teach its members