1 : a person who does something (such as a sport or hobby) for pleasure and not as a job
She played soccer as an amateur before turning professional.
These photos were taken by both amateurs and professionals.
2 : a person who does something poorly : a person who is not skillful at a job or other activity
The people running that company are a bunch of amateurs.
Only amateurs make this kind of mistake.
He's a mere amateur when it comes to cooking. [=he doesn't know how to cook well]
— amateur adjective, always used before a noun
an amateur competition [=a contest for amateurs]
They competed at the amateur level.