Question

What is a loose-fitting dress that hangs straight down from the shoulders and without a prominent waistline called?

Answer 1

i believe it is called a shift or the next closest thing would be a sheath. a shift is straight an has no inner shaping at the waist line but the shoulders are more prominent in a sheath. I hope this helps! do you mind me asking why you are asking?  

Answer 2

I believe that you are describing a swing dress. Hope this helps! :)