a.

1. 职业（上）的；从事特定专业的[Z][B]
2. 职业性的，非业余性的[Z][B]
3. 很内行的；极称职的；高水平的
   a highly professional administrator

   一位非常内行的管理人员

4. 【贬】以……为业的，擅长……的
   He is a professional complainer.

   他是一个发牢骚专家。

n.[C]

1. 职业选手
2. 专家，内行

adj.

1. relating to or belonging to a profession.
   ▸worthy of a professional person; skilful or competent.
2. engaged in an activity as a paid occupation rather than as an amateur.
3. informal, derogatory habitually engaged in a particular activity:
   a professional time-waster.

n.