"Fermented soybeans" refers to soybeans that have undergone a natural process in which they are left to sit and develop beneficial bacteria. This fermentation process enhances their taste, texture, and nutritional value. Full definition
Soy sauce - a sauce made from fermented soybean paste, salt and enzymes (read the label and investigate the brand as many companies chemically ferment their soy sauce, which isn't a true fermented soy sauce) (realfoodgirlunmodified.com)
Quantification and odor contribution of 2 - furanmethanethiol in different types of fermented soybean paste miso. (whfoods.org)