What words that end with the prefix - ult?

You're thinking of the suffix "-ult", not the prefix "-ult". There is no prefix "-ult".

Here are some words that end in "-ult":

* Result

* Consult

* Assault

* Insult

* Adult

* Fault

* Vault

* Halt

* Cult

* Bolt

* Mult (short for "multi-", used in some technical contexts)

* Gault (a type of clay)

Let me know if you have any other questions!