a person who tries to please or amuse
"The local street performer, an entertainer known for his juggling act, delighted the crowd with his colorful balloons."
A person who entertains others, esp. as a profession, as a singer, actor, presenter, dancer, musician, magician, comedian, etc.
"The local theater hired a famous jazz entertainer to close out the summer festival."
The word comes from the verb "entertain," with the suffix "-er" added to indicate a person who performs that action. Originally, it referred to someone who provides amusement or enjoyment for others.