Formal:
* Jamais: This is the most common and general way to say "never."
* Nullement: This means "not at all" and can be used to emphasize that something never happened.
Informal:
* Pas du tout: This means "not at all" and is a more casual way to say "never."
* En aucun cas: This means "in no case" and is a stronger way to say "never."
Here are some examples:
* Je n'ai jamais vu ça. (I've never seen that.)
* Je n'irai jamais là-bas. (I will never go there.)
* Nullement, je ne suis pas d'accord. (Not at all, I don't agree.)
* Pas du tout, je n'ai pas faim. (Not at all, I'm not hungry.)
* En aucun cas je ne te mentirai. (I will never lie to you.)