How can I say "You must not do it" as imperative

Question

I learned that the only Korean grammar that can express the meaning "must" : (으)면 안 되다.

But I am not so sure if this can mean an absolute "must" in this case as the meaning for it should be "If..., not OK" and I think it is not strong enough.

Example: 이렇게 하면 안 돼! -> Don't ever do it( or else you will suffer a lot,etc.)

I am actually asking for a Korean equivalent for a Chinese vocabulary. This word can be used in any situation as long as the meaning "must" and the imperative mood is conveyed. If you are interested, it is 千萬(it is not meaning 10 million here, but only a word to intensify imperative negation)

Example where it is used:

1. A friend recommended an insurance service. However I doubt that the company is actually trustworthy, so I tell him "(You must not)Don't ever trust them (千萬不要相信他們)"

2. A child wants to play Bungee jump. This child's parents are afraid of the potential dangers of the game, so they said "(You must not)Don't ever play this (千萬不要去)"

I could think of the word 절대(로), such as "절대로 그 놈들을 믿지 마", to express the meaning "You must not do it". But I think it is a bit weird. (It is just a feeling, I am not sure)

Anyone who can tell how I should express the word stated above?

Answer 1

I will attempt to answer the question here.

As has been discussed in the comments and in the question, 절대 하지 말다 and all of its various conjugations can act as a strong negative imperative. I would say that 절대 is maybe the closest word in Korean to express a meaning like unto that of 千萬. This is not a literal equivalence of course; rather, it is just what I (in my limited knowledge of Chinese) feel is the best Korean equivalent.

One thing I will say is that I once had an older Korean gentleman tell me (while laughing) the following (as close as I remember):

"절대란 말을 절대 쓰지 마!"

In other words, whatever you do, don't use the word "절대." These were of course just his thoughts, so take them however you will. Since I am not Korean, it is hard for me to speak to that exact nuance.

In terms of the hanja for 절대 (絶對) itself, I will leave the specifics of translating the meaning to someone more expert than I. Loosely translated I would say though that 絶對 holds a meaning of something like "there is no alternative," or "by no means."

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As has been touched on, the form -(으)면 안되다 is one way of expressing negative feeling towards and action, even to the extend of negative command.

이 차에 디젤을 넣으면 안 됩니다 (You must not put diesel fuel in the car).

One other form that I will mention is the form -아/어서는 안 되다. This form is overall more rare than -(으)면 안되다 I believe. It also has a slightly softer feeling I think. Instead of a hard "do not," it is often used as a softer "should not."

우린 공공장소에서 사적인 대화를 해서는 안돼.

(We should not discuss personal matters in public).

-

남을 괴롭히는 것은 해서는 안될 나쁜 짓이다.

(We really should not belittle people).

I provide this form as a matter of contrast to (으)면 안되다.