What's in a name?

Hydrosol or Hydrolat
Guérain (1886) defined the word hydrolat as a pharmaceutical term. His definition of a hydrolat is a colorless liquid, which is obtained by distilling water with (fragrant) flowers or plants. A hydrolat is always a product of steam distillation. The official definition of the word hydrolat in French law is: "aqueous distillate remaining after steam distillation, after the separation of the essential oil and water has been carried out."

The word hydrolat consists of two parts: “hydro” comes from the Greek for water, “lat” is a word from Old French for milk. So, you can conclude that this terminology comes from the milky turbidity of a hydrolat just after steam distillation.

Hydrolat or Hydrosol
The word hydrosol is widely used in the English language, specifically in the US, when referring to distilled plant waters. The word is wrong, because it is a generic (insufficiently specific) term and therefore applies to a wide range of products. The definition of hydrosol in Chambers Science and Technology Dictionary is "a colloidal solution in water" (which is a very broad term).

“Hydro” comes from Greek and means water and “solvere” is Latin for to loosen. A colloidal solution is a dispersion (a mixture in which one substance is finely divided into another substance), in this case liquid substance, characterized by very small particles (between 0.2 and 0.002 microns).

Due to this explanation, a hydrosol could also be obtained, for example by centrifuging an essential oil for a long time in water, whereby eventually some water-loving ingredients transfer to the water. But soaking, for example by making an infusion or tea, could also be applicable. A chemical process with synthetic substances could even fall under the heading of colloidal solution.

That is why we use the word hydrolat, as being the Dutch translation of the French or German word hydrolat. By this we mean the process of obtaining a plant water by means of distillation of fresh plant material. We therefore conform to the definition as laid down in the French pharmacopoeia.