What is the prefix for harmony?

There isn't a single, universally accepted prefix specifically for "harmony." However, depending on the context, you can use various prefixes that convey related meanings:

For musical harmony:

* Eu-: meaning "good," "well," or "pleasant" (e.g., euphony)

* Harmo-: specifically for harmony, used in terms like "harmonious"

For general harmony or agreement:

* Syn-: meaning "together" or "with" (e.g., synergy, synchronize)

* Con-: meaning "together" or "with" (e.g., concord, consensus)

Ultimately, the best prefix depends on the specific nuance you want to convey.