The number of people in a formation leads to it being called an N-way, where N is the number of people. So a group of 5 skydivers will make a 5-way.
Different people have different ideas of how many people need to be in the formation for it to be called a “big way”. I have heard 16 used as the line, although since “big” is subjective, so is “big way”. I personally think it is a big way if you need more than one airplane to get everyone there, but that technically has a different term. It is called a “formation load” because the airplanes fly in formation to let all the skydivers out close to each other and meet up in free fall.