IPA: /fərˈmɛntəbl/
KK: /fərˈmɛntəbl/
Capable of undergoing fermentation, which is a process where sugars are converted into alcohol or acids by microorganisms.
The yeast used in brewing is fermentable, allowing it to produce alcohol from sugars.
Fermentable → It is formed from "ferment" (from Latin "fermentare", meaning to leaven or cause to rise) and "-able" (meaning capable of). The word "fermentable" means capable of undergoing fermentation.
Think of something that is 'capable of' ('-able') 'causing to rise' ('ferment') — that's why fermentable refers to substances that can undergo fermentation.