Como dizer "Professor particular" em inglês

(Private) tutor
1. Um responsável legal ou alguém de confiança da família responsável pelos custos e todo processo relacionado a educação ou iniciação acadêmica de um discípulo ou aluno;
2. Alguém que dá aulas particulares para 1 pessoa ou um grupo fechado.

Private teacher
1. Alguém com um profundo conhecimento em determinada área responsável em ministrar aulas particulares;
2. Alguém que presta serviços particulares de ensino pré-universitário;

Private professor
- Alguém com formação acadêmica na área letiva / atuante e que presta serviços educacionais particulares;

You should read:
(1) https://www.englishexperts.com.br/e-cor ... e-teacher/
(2) como-dizer-aulas-particulares-em-ingles-t1294.html

* Em termos de aulas com preços acessíveis e praticidade, recomendo o uso do termo, sendo este o mais utilizado:

He is looking for a private teacher for English studies.
Ele está procurando um professor particular de inglês.

He attends English classes with a private teacher.
Ele tem aulas de inglês com um professor particular.

* Agora se é do desejo de alguém ter aulas com alguém com formação acadêmica, então recomendo o uso dos termos tutor ou private professor.

_

Teaching includes a more general concept.
If we look for a special teacher, especially in MED countries, we need to be more specific, depending on the occasion.

Nowadays, to teach is not only a matter of academic background, but also a competence and reference.

Teacher: someone whose job is to teach, especially in a school;

Professor:
(1) teacher at a university or college (AmE);
(2) a teacher of the highest rank in a university department (BrE).
_

You may find it interesting to know about the teaching / academic degrees:

1) Teacher: someone who teaches as their job, especially in a school.
Ex.: a high school teacher;

2) Principal ( also headteacher British English ): the teacher who is in charge of a school or college;
Ex.: The teacher sent him to the principal’s office.

3) Tutor: someone who gives private lessons to one student or a small group of students. In Britain, a tutor is also a teacher in a university.
Ex.: They hired a tutor to help him with his English. | Your tutor will help you find a subject for your essay.

4) Lecturer: someone who teaches in a university or college.
Ex.: (University) lecturers aren’t very well paid.

5) Professor: a teacher in a college or university. In Britain, a professor is a high-ranking university teacher, especially one who is head of a department;
Ex.: She was professor of linguistics at Cambridge University.

6) Instructor: someone who teaches a sport or a practical skill such as swimming or driving;
Ex.: He works as a ski instructor in the winter. | a driving instructor

7) Coach: someone who helps a person or team improve in a sport;
Ex.: She is a professional tennis coach

8) Educator (especially in American formal English): someone whose job involves teaching people, or someone who is an expert on education;
Ex.: Most educators agree that class sizes are still too big.

9) Trainer: someone who teaches people particular skills, especially the skills they need to do a job;
Ex.: a teacher trainer | Many companies pay outside trainers to teach management skills to their staff.

10) Governess (archaic): a woman who lived with a family and taught their children in past times;
Ex.: As a governess, Charlotte Brontë received twenty pounds a year.

REFERENCES:
(1) CARVALHO, Ulisses Wehby de. Armadilhas de Tradução. 2013.
(2) Pearson Education. English dictionary. 2014.
(3) Oxford Living Dictionary.