must not (do), should not, do not
Verb Dictionary Form +
This grammar point is used to express a strong, authoritative prohibition or a command that something must not be done. It is a formal, classical-sounding expression often found in signs, rules, or formal warnings.
Verb Dictionary Form
Attaching
入る
Do not enter.
ごみを捨てる
Do not throw away trash.
When using the verb する (to do), it often becomes す
Verb Dictionary Form +
This form is used when the prohibition acts as an adjective to modify a following noun. It describes a noun that 'should not' or 'must not' be subjected to a certain action.
Verb Dictionary Form
By using
許す
An unforgivable act.
欠く
An indispensable person (a person who must not be absent).
Similar to the sentence-ending form, する becomes す