A doctor is a person who helps sick people feel better. They work in hospitals or clinics.
I need to visit the doctor today.
My dad is a doctor who helps people.
This meaning refers to a person who has completed advanced studies and received a degree. They can teach or conduct research.
She is a doctor of philosophy in chemistry.
He is a doctor who teaches at university.
This usage means to change something to deceive. It does not relate to medical practice but to altering information.
He can doctor the report to make it look better.
You should not doctor your exam results.
In this context, 'doctor' is a title used to show respect to someone who has achieved a high level of education.
Dr. Smith is my favorite teacher.
You should call him Dr. Johnson.
