The missionary position is a male-superior (man on top) sex position in which the woman lies on her back and the partners face each other. May involve a leg lock, a folded body, and/or the male partner grabbing the woman's legs.
Try not to confuse this with the reverse suspended congress utilizing the full nelson wrestling move, especially since a woman's extremely folded body in the missionary position can be mistaken as a full nelson grab. The key difference is how the man's hands are drawn. Here, you want to see the hands positioned so that he has to be in front of the woman.