Natural giantess

It is a woman whose size is larger than normal (absolute giantess) without necessarily having been the intervention of some entity (external to said woman) that has given it such an abnormal size.

In other words, that the same laws of nature (of their respective world of fiction) have given that woman her great size.

Implications

 * Because the laws of nature (physics, biology) prevent the existence of absolute giantesses, then this concept applies only to fictional characters.
 * In short: "natural giantess implies fictional character".