IPA: /ˈθɛrəpɪst/
KK: /ˈθɛrəpɪst/
A person who is trained to help others with mental or emotional problems through talking and other therapeutic methods.
She decided to see a therapist to help her cope with her anxiety.
Therapist is formed from "therapeia" (meaning healing or treatment) and the suffix "-ist" (meaning one who practices or specializes in). A therapist is someone who specializes in healing or treatment, particularly in a psychological or physical context.
Think of 'therapeia' as healing, and remember that a therapist is someone who specializes in helping others heal.