It is a curious fact, but there are no legal definitions of natural and this provides much subject for debate and litigation as law enforcement agencies argue interpretation with marketers of products placed onto the market.
We would define natural as any material that is harvested, mined, or collected, and which may have subsequently been washed, decolorized, distilled, fractionated, ground, milled, separated, or concentrated to leave a chemical or chemicals that would be available and detectable in the original source material. It is also the modification of natural material by the action of microorganisms, enzymes, or yeasts to modify or increase the yield of material by this process.
Naturally derived materials are defined by the use of a natural raw material as the starting point in a chemical process to produce a newchemical or chemicals that in themselves may not be available in nature or in the starting material.
Nature identical material is a substance that has been produced synthetically, not usually from a natural starting material, to produce a material that is identical to that naturally occurring in nature.

The concept of 'natural' is complex and lacks a universal definition. However, an ISO standard for natural ingredients has been established.

ISO 16128-2:2017 describes approaches to calculate natural, natural origin, organic and organic origin indexes that apply to the ingredient categories defined in ISO 16128‑1. This document also offers a framework to determine the natural, natural origin, organic and organic origin content of products based on the ingredient characterization.

ISO 16128 provides guidelines on definitions and criteria for natural and organic cosmetic ingredients and products. These guidelines are specific to the cosmetics sector, taking into account that most existing approaches written for the agricultural and food sector are not directly transferrable to cosmetics. They apply scientific judgment and offer principles towards a consistent logical framework for natural and organic cosmetic ingredients and products incorporating common approaches employed in existing references. The purpose of these guidelines is to encourage a wider choice of natural and organic ingredients in the formulation of a diverse variety of cosmetic products to encourage innovation.

Source: The internal and external use of medicinal plants - Anthony C. Dweck, FLS, FRSC, FRSH and iso.org

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