The first thing to understand here are the basics of translating in ANY language. You must first understand that words do not have mutual exclusivity in differeing languages; i.e. 1=/1. What I mean to say is that in English we use the word "self" to communicate a specific meaning. In Korean, they may have 10 words that do the same idea, but in slightly different ways.
Korean is much more complicated, because you are really dealing with two languages. You see, until 1443, the Korean people used the Chinese writing system exclusively and many of their words were influenced by Chinese. These "borrow words" are sometimes still written in Chinese, in Korean, called Hanja. Particularly Martial arts terms are still written in Chinese in some texts. Many academic texts in Korean are written strictly in Chinese. The thing is, these Chinese or Hanja characters are pronounced differently in Korean than they are in Chinese. Therefore, some words have two different "spellings" or as you would think of - symbols.
So, when I say that 身 means person, I mean that the Hanja character, pronounced "shin" in English and spelled 신 in Hangul (Korean written language). The word hosinsul comes from Hanja, so the characters and pronunciations differ slightly from strict, every day Korean since this is a martial arts term. If you are familiar Tae Kwon Do, you will notice that many of their words for techniques differ from other Korean styles, this is because some organic KOREAN words were created to describe these techniques, instead of using the Chinese influenced Hanja words.
So, to answer your question about the word 몸 meaning self. That begs a lot of questions. First of all, what is the hangul spelling? Is it 몸, 멈, 몀, 묨? Or something else? I realize that you may not read hangul, but depending on who you heard this from, it could be any of these...believe it or not, most American's pronunciation of Korean is pretty bad. And even if you "heard it from a Korean," no offense, but I hear this A LOT and most of the time, it was either mis-heard or mis-respoken. That is not to say that the person who told you this was wrong....it is just that I have never heard of it that way. It could be slang, it could be from someone much more fluent than me, it could be another part of speech, who knows....Think about it, how often do we use the SAME word for multiple parts of speech? Other languages may use COMPLETELY different words. In fact, that is often true in Korean, the verb and noun will sound nothing alike. (although, usually the ending -hada makes the verb). Here are the results from an online Korean dictionary when looking up "self"
A 같은 재료의, 단색의, 나무로 된, 섞이지 않은
N 자기, 자기의 이해, 본성, 본인, 단색의 꽃, 단색의 동물, 자연색의 꽃, 자연색의 동물
PRON 자신이라는 뜻
V 자가 수분시키다, 자가 수분하다
I assure you that none of the words here are pronounced "mom" or any variation thereof. The closest that I know of is 나 자신 (na chasin) which means "myself." Like I said, I am far from fluent, so there may be some who know of it a different way.
If you are interested in a reference, your first step will be to learn to read Hangul. That is easy, you can even learn that from wikipedia....but then you can pronounce, but you can't read. So a simple Korean-English dictionary will work. But like many translation dictionaries, it will include a small fraction of the words in Korean, so you need a regular Korean dictionary. I generally use Korean search websites...but you need to read hangul for that. You can also get a Korean/Hanja dictionary....that's even harder because they have even less words in them. I use a chinese dictionary for a lot of it, find the character, look it up in a Chinese dictionary, then use open okpyon to try to make the jump to Korean.
Luckily since hosinsul is a standard Korean Martial Arts term, it is in my personal Korean martial arts dictionary, which I built from a variety of references. If you are interested in a more reliable reference than my excel file, you can use
zkorean, but searches are limited without paying. Here is a SMALL portion of the results from "self" that relates to martial arts. ZKorean unfortunately does not include Hanja.
self-protection
- hoshin

self-defense
- hoshin

to protect one-self
- hoshinhada

for self-protection
- hoshinyong-euro

for use in self-defense
- hoshinyong-euro

sword for self-protection
- hoshindo

art of self-defense
- hoshinsul

By the way....the strictly KOREAN word for Self Defense (with no influence from Hanja or Chinese), is jagi bang-eo (
자기 방어).
I hope this helps....