Butterfly position (butterfly position) is a variation of missionary position most often used by every couple.
If this position is done by humans then it is called Butterfly.
It is unclear why this position is called butterfly. Probably because the formation of this position looks like a butterfly when viewed from above. Can also because the shape of a female pair of legs that expand like a butterfly wings that fly beautifully.
In this position of missionary variation, the male couple stands upright. While the position of the female partner lying with his back on the edge of the bed, with the exact position of the buttocks edge of the bed, if done in bed.