The Zu Omen Def

I know that Zu is a manufacturer of loudspeakers, but what does "Omen Def" mean. I have no idea, but a pair of these speakers was producing a lively sound at TAVES. At $3400/pair ($2900/pair show special), the price seemed eminently reasonable. They were playing vinyl, courtesy of a KLM 15 turntable and Denon 103 Grade 2 (yes, it's still being made) cartridge.