1.2.3　Root

The main part or stem of a word is called a“root”.A root conveys the essential meaning of the term and usually indicates an organ，tissue，or condition.For example，in the word“hypertension”，the prefix hyper-means“high”or“over”，and the root“tension”refers to“pressure”，so the word“hypertension”refers to“abnormally high blood pressure”.Nearly all medical terms contain at least one root.When a prefix is absent，the term begins with a root.(https://www.daowen.com)