This is the foundation of the medical word and all medical words must have at least one word root. It provides the primary meaning of the medical word. 

There can be multiple medical word roots that have the same meaning, for example:

• Dermat which refers to the skin.
• Cutane which refers to the skin.

These word roots are associated with the intestinal tract:

• Gastr which refers to the stomach.
• Enter which refers to the small intestine.
• Col which refers to the large intestine.

Most word roots are written with their combining form. The combining form is created when the word root is combined with a vowel, most commonly the letter "o", which enables two or more word part elements to be combined with it. 

Examples of word roots within their combining form are (commonly formatted as "/o"):

• Dermat/o
• Cutane/o
• Gastr/o
• Enter/o
• Col/o

The word root with its combining form now can be combined with another word root or a suffix.  For example:

• Gastroenterologist

The word root of gastr/o was combined with the word root enter/o. Then the combining form of enter/o was combined with the suffix -logist.  Together, the word means a healthcare specialist who studies and treats disorders of the stomach and intestines.

A suffix is a word part that is added to the end of the combining form of a word root that changes the meaning of the word root(s). All word roots will have a suffix, which defines or provides meaning to the word root(s). Suffixes are commonly designated with a hyphen and then the suffix word part.  For example:

• -ectomy which means surgical removal.
• -itis which means inflammation.
• -logy which means the study of.
• -oma which means mass, tumor, cyst. 

For example, let's use the medical word root for liver, hepat/o, and see how a suffix can change its meaning:

• Hepatectomy: surgical removal of all or a portion of the liver.
• Hepatitis: inflammation of the liver.
• Hepatology: study of the liver.
• Hepatoma: tumor or the liver.

A word part at the beginning of a word root that modifies its meaning is referred to as prefix. A prefix is designated by the word part followed by a hyphen. Not every word root needs a prefix, but every word root needs a suffix.

Examples of common prefixes are:

• "Hyper-" which means excessive, above normal.
• "Hypo-" which means below, beneath.
• "A-"; "An-" which means without, lacking.
• "Dys-" which means difficult, painful.
• "Eu-" which means good, well.

Examples of these prefixes within medical terms:

• Hypertension means an increased average of blood pressure.
• Hypotension means below-average of blood pressure.
• Anaerobic means without oxygen.
• Dyspnea means difficult, labored, or painful breathing.
• Eupnea means good or healthy breathing.