A méchanquien is defined as a human who has part of their body replaced with a mechanical alternative; this can be any bodily component, from limb to process to bodily function. The group contains a wide swath of humanity, from those with a heart-pump or mechanical eye to those almost entirely comprised of mechanical parts.

There is a controversy among unméchanquiens whether people who use smaller, removable mechanic assists—such as eyeglasses, walking-sticks, and the like—should be counted among the numbers of méchanquiens.