So Zarathushtra uses "Ahura" when he speaks of "Existence" and "Mazda" when he speaks of "Mind".
When - rarely - used together in the Gathas, they simply are combined to strengthen together in an obvious wordplay (one word is feminine and one word is masculine and they are kept as such even when combined).
So Ahura Mazda is when existence and mind strengthen each other, as in a Hegelian way, to "be the world and make sense of the world in one go".
I would prefer the translation "Existence as manifested through Mind". But why translate at all?
I-m spending the weekend crossreading books on religion by Peter Sloterdjik and Slavoj Zizek. Sloterdjik wins hands down!
2009/11/28 Special Kain
I'd like to have this settled once and for all: What does «Ahura Mazda» mean in English? Ali Jafarey claims that it means «The Wise (Mazda) Lord (Ahura)», Parviz Varjavand and I seem to agree that «Ahura» simply means «existence (that which exists)» and «Mazda» is «wisdom». Now I've read somewhere that it should mean «the force that creates (Ahura) wisdom (Mazda)». So we can all be sure that Mazda is «wisdom», but what about Ahura? There's a huge difference between existence and creativity (and mastery).