All words have a foundation, called a root or a root term. The root is the minimal expression of a word that conveys a specific meaning. The word [hepa] does not mean liver, but the root term [-hepat-] does. There are some root words that have two presentations, like [-card-] and [-cord-], both meaning "heart", and even three presentations such as [-uter-], [-metr-], and [-hyster-], all of them meaning "uterus". All these following words have root terms meaning "uterus": periuterine, endometrium, and hysterectomy.

In medicine, surgery, and human anatomy there are several cases where there is more than one root term for the same organ. The terms [lienectomy] and [splenectomy] both mean "removal of the spleen", as the root terms [-lien-] and [-splen-] both mean "spleen". The same is the case in the following pairs: [-nephr-] and [-ren-], meaning "kidney"; [-cyst-] and [-vesic-], meaning "bladder";  [-pneumon-] and [-pulmon-], meaning "lung"; etc.

Root terms can also be combined to form complex medical terms, such as [gastroenterology], [leiomyomata], [cholecystectomy], [dacryocystolithectomy], [nephroureterocystourethrectomy], etc. To do this there are specific rules for combination.

For information on how to read medical words, click here.