Ritual and respect
Nak muay
นักมวย
What it means
A boxer, in the Muay Thai sense. Used for someone who fights, not for everyone who trains. Foreign fighters are often called nak muay farang.
The distinction matters at a camp. Calling yourself a nak muay after a week of holiday training will read as a claim rather than a description.
Nobody will correct you out loud, which is exactly why it is worth knowing.
Related
Words that go with it
Farang
The everyday Thai word for a Westerner. It is descriptive rather than an insult in normal use, and you will hear it constantly at any camp that takes visitors.