A non-exhaustive list of them:
- Modulo and modulus in elementary number theory
- Modulus of a complex number, a vector etc.
- Module in abstract algebra
- Modular form
- Moduli space
- Young's modulus (though that's off topic)
I have searched for the etymology for them, and they all came from latin "modus" (and its declensions and derivatives). But most dictionaries don't bother to explain why those names were chosen.
The question is: Is there a reason why the latin root is repeatedly chosen to name the large variety of concepts?