If you are looking for a free Thai lessons online, you will hear teachers call themselves ‘ครู’ /kroo/
ครู /kroo/ is originally from a Pali ครุ /kru/ or Sanskrit คุรุ /kuru/. It means heavy; someone with respectful behaviors and a teacher.
Normally people use it to call teachers in kindergartens and schools. It can be a noun and a pronoun. That means students will call their teacher ‘ครู’ /kroo/. It’s pretty common to hear teachers call themselves ‘ครู’ /kroo/ when they talk with their students, too.
What’s about อาจารย์ /aa-jaan/?
Do you know ‘www.ajarn.com’? It is a famous job-listing website for foreign teachers in Thailand. I think that you can guess by now how the word ‘อาจารย์’ /aa-jaan/ relates to teaching job.
อาจารย์ /aa-jaan/ is from Sanskrit meaning a role model; a teacher and an instructor.
Normally, we use this word to call lecturers or professors in colleges and universities. We also use it to address someone as a master of any kinds of knowledge although that person might not teach for a living.
I hope that you enjoy learning Thai with your present ‘ครู’ /kroo/ or ‘อาจารย์’ /aa-jaan/. J
P.S. Since there is no official, mandatory standard of Thai Romanization, not like Pinyin for Mandarin. That’s why, you might see various ways of romanizations. Some very academic schools might prefer to use phonetic symbols. Other schools prefer different romanizations. I also prefer to use the romanization but my version might not be exactly the same as any others.
Anyway, if you are certain that you will live here and you prefer to blend in the society or at least understand them from the eyes of local people, learning the language is the first door for you. Being able to read Thai is also very important in order to improve your comprehension in language and culture in a long run.
I wish you luck! LOL