I'm not sure it's a miniskirt or even a skirt
Well, obviously it's not a skirt of any sort if it goes over your shoulders...
Technically, it's what figure skaters tend to wear: a one-piece swimsuit or leotard where the lower part additionally has a long brim that makes it look like a dress.
What Nhan (or Uhura in ST5:TFF) wears is a miniskirt, though.
Timo Saloniemi