What is a prefix for not true?

There isn't one single, universally accepted prefix for "not true." However, depending on the specific context and nuance you want to convey, you could use several options:

General Negation:

* un-: untrue, unreal, unverified

* in-: incorrect, invalid, inaccurate

* non-: non-existent, non-factual, non-authentic

Other Options:

* dis-: disproven, disconfirmed

* mis-: misrepresented, misinformed

* pseudo-: pseudo-scientific, pseudo-historical

The best prefix will depend on the specific word you are modifying and the meaning you want to convey.

For example, if you want to say that something is not true, you could say it is untrue, incorrect, or non-existent. If you want to say that something is not genuine, you could say it is unauthentic or fake.

It's also important to consider the specific context of your writing. For example, in a formal setting, you might want to use more formal language, such as "invalid" or "inaccurate." In a more informal setting, you might use more casual language, such as "not true" or "false."