What color is this dress

First a little color theory.. When you have two colors that are complimentary (opposite from one another on the color wheel) then your eye quickly goes back and forth from each color and each color looks it's most vibrant because it is next to its opposite.  Lavender's compliment would be a warm green-  if you can't properly see green (which is relatively common) than you will likely view it's complementary as a different color than it actually is when they are next to each other..  Also when we see colors with a white background they are going to appear darker and more muted than they are (18%grey-background will show true colors). Also we are all see this on different calibrations of RGB as opposed to IRL we would all see the same calibration of CMYK reflected off the dress 

Everything is relative.. my vote lavander and a warm yellow ochre green 

On the left First "lavender dress" that comes up on search - on right original (albeit cropped) photo of #thedress