Pretreatment refers to any processes or procedures done prior to the main treatment stage. There are various synonyms for this word depending on the context and situation. These synonyms include preliminary treatment, pre-treatment, preparatory treatment, preliminary stage, and preparatory stage. For example, in water treatment, pretreatment refers to the removal of solid and organic materials before disinfection and filtration. In medicine, pretreatment refers to the medication given before the primary treatment to reduce side effects or improve the effectiveness of the main treatment. Regardless of the field, pretreatment is necessary to ensure optimal results for the main treatment or procedure.