Targets, concepts, principles, methods, historical evolution, interactions with other sciences, systems, and implications on society are common fundamentals to any science or scientific field. With regard to concepts they can be expressed differently by people from different educational backgrounds and experiences, but preserving the fundamental ideas. Concepts can also evolve over times. This paper shows the changes undergone by the concept of peloid since the creation of this term and meaning in 1933, and the arguments that justified those changes. Also, the systems or classifications of peloids have evolved since the first classification proposed in 1937. This paper shows the classifications which have been proposed since then and the fundamentals on which they were based upon. Also a new, short and concise definition and classification of peloids are proposed.
Relevant inconsistencies are found in the scientific literature regarding both nomenclature and definition of terms used in health resort medicine or spa therapy, skin care, balneology, balneotherapy, hydrotherapy, mud therapy, pelotherapy, thalassotherapy, climatology, and climatotherapy. Even the international general acceptance of these methods and terms is not fully recognized. A glossary with the terms and corresponding technical definitions does not exist. A glossary in English, the idiom worldwide used for science communication, prepared by an ad hoc Working Group constituted by the authors of the present paper is herewith proposed.