What is the French word for will?

Answer 1

It depends on what you mean:

If you are referring to the legal document that bequeaths wealth to your heirs (I sign this will to give my children the estate), it would be: "testament".

If you are referring to the drive or desire to do something (I am going to survive by sheer force of will), it would be "volonté".

If you are referring to the future simple tense in English (I will eat), there is no single French word for this. The future tense is something that is conjugated into the verb. The Essential Guide to the French Future Tense provides a lengthy discussion on how to do this.

Answer 2

will as in last will and testament is un testament.

will as in the future tense: there is no word for will. Verbs are conjugated to create the future tense.