What is Sool?

Hanja for sool
Hanja for Joo/Sool which in itself resembles a bottle.

The Sool Company takes its name from the word in Korean which refers to alcohol. Like many of the traditional expressions which refer to recipes, techniques and styles of Korean alcohol, there are some variations on its meaning and interpretation. This article hopes to clarify the meaning of the word Sool, for those new to the world of Korean fermentation.

In modern Korean, the word Sool is used to refer to all types of alcohol. Including makgeolli, soju, beer, wine and whisky.  There is no differentiation between domestic and imported alcohols in terms of its use. However, it has a meaning that is tied to the history of the production of fermented alcohols of Korea.

As is true internationally, the history of fermentation in Korea predates an understanding of the biological and chemical processes that the raw ingredients undergo. Therefore, a lot of the terminology and nomenclature used to describe processes or reactions that are invisible or inexplicable to a layperson, either just explain visual phenomena or have a spiritual quality.  This is true of the historical brewers from the Joseon dynasty.

Brewing in Korean History

Brewing was commonplace before the Joseon period of Korea (Founded in 1392). However, it flourished heavily due to Royal restrictions on brewing and the subsequent surge in illegal homebrewing that followed. Most of our traditional recipes and terminology used for describing Korean brewing techniques, processes and measurements come from this period.

Nowadays we have an understanding of the alcohol fermentation process. In its simplest form, it is the conversion of sugars into ethanol, predominantly with a Saccharomyces yeast being the instigator of the change. Through that microorganism’s consumption and breakdown of sugar molecules into ethanol, we get other chemical byproducts and the production of heat.

One of these byproducts is key to our understanding of the word Sool and its origin in the perception of fermentation by Joseon dynasty brewers. Carbon dioxide (CO2) is the most recognizable chemical product of a yeast driven alcohol fermentation process as it takes the form of vigorous and visible bubbling. It is not dissimilar to the effect of boiling a liquid.

The Origins of The Word ‘Sool’

Without a knowledge of chemistry or biology, the association of heat and boiling when observing the CO2 output of yeast would be a natural one to make which is why brewers in the 15th century referred to brewing with terms relating to fire.

Hanja Character for Water.
Hanja Character for Fire

[quote align=”left”]In Korean the word for water is mul/mool (물), however the Chinese expression su/soo (수) was and is still heavily used. The Korean word for fire is bul/bool (불).[/quote]

When observing the effervescence of fermentation Joseon brewers understood that they had used their brewing technique to unlock some elemental fire that was contained within their water. They created boiling without the use of external heat. They used the expression soobool (수불) to refer to this.

Most homebrewers and families communicated their culture, stories and recipes in the oral tradition, so there are very few early Joseon records of brewing practices. However, there is a record from 1446 referring to soo-ul (수을) (1) which is a contraction of Soo and Bool. Fire & Water.

The Modern Use of The Word ‘Sool’

This word persisted over the centuries but found itself subject to further contraction. Finally evolving into the single syllable of sool (술).

The etymology and the historical usage of the word ‘Sool’ are bound to the mixture of grain, nuruk & water, and reflects the brewer’s understanding of the processes in play during the fermentation process that followed. Recently, terms have become popular, even standard which delineate this alcohol based on other criteria. Jeontongju (전통주) translates to  Korean Traditional Alcohol (2). Minseok Ju (민속주) translates to Folk Alcohol whereas another common term is Woorisool (우리술), meaning ‘Our Alcohol’, with the ‘our’ meaning Korean.

These expressions are only the most common among a large number of alternatives and variations of descriptions of alcohol that has a Korean heritage. None of these are particularly comfortable when translated and used frequently in English. The word Sool has its roots in the traditional Korean fermentation style and is distinct and simple enough to pronounce by English speakers. Hence our motivation to choose this term for the promotion of Korean alcohol internationally, much in the same way Japanese alcohol is branded as ‘Sake’ to global markets, as well as why we designated it as the keyword in our company’s name.

We hope this article clears up at least one expression you may come across in our material.

For a deeper understanding of the basics of sool making, you can check out our free Makgeolli Homebrewing Crash Course where you will learn everything you need to know to make your own sool.


  1. 류인수, 2014, 한국전통주교과서, 교문사.
  2. The Korean nature of it is implied
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