UFO in this context (for those of you who don't spend all your free time sewing) means "un-finished object." The dress at the left in this picture is a UFO of mine. I made it up in a heavy raw silk, in black, which I think is what led to it descending to the UFO netherworld. The fabric isn't stiff enough (it's heavy but floppy) and, frankly, I find sewing with black fabric boring. (Click on the image to see it full-size in a new window.)

I may yet dig it out and finish it up, though, because the lines are gorgeous. You know the person who designed that went home pleased with herself that day.