MeSH vocabulary is divided into four types of terms. The main ones are the "headings" (also known as MeSH headings or descriptors[1]), which describe the subject of each article (e.g., "Body Weight", "Brain Edema" or "Critical Care Nursing"). Most of these are accompanied by a short description or definition, links to related descriptors, and a list of synonyms or very similar terms (known as entry terms).