A word root is the primary building block of a medical term and refers to the body part or body system to which the term is referring. Some words contain more than one word root. The order is generally dictated by common practice. As you practice throughout this course, you will learn more about how to determine the order of word roots. Word roots will be further discussed in more detail in each chapter as they relate to specific body systems.

A combining vowel is a word part, most often the letter “o,” that helps pronunciation.

Common Word Roots and Their Combining Vowel

Here is a list of commonly used word roots and their combining vowel. It is helpful to memorize these components as you build your knowledge of medical terminology.

• abdomin/o: Abdomen
• andr/o: Male
• angi/o: Vessel
• arteri/o: Artery
• arthr/o: Joint
• audi/o: Hearing
• bronch/i, bronch/o: Bronchus/lung
• carcin/o: Cancer
• cardi/o: Heart
• cholecyst/o: Gallbladder
• chrondr/i, chrondr/o: Cartilage
• col/o: Colon
• cysti, cyst/o: Bladder or cyst
• cyt/o: Cell
• duoden/o: Duodenum
• encephal/o: Brain
• erythr/o: Red
• esophag/: Esophagus
• gastr/o: Stomach
• glyc/o: Sugar
• gynec/o: Female reproductive system
• hemat/o, hem/o: Blood
• hist/o: Tissue
• hyster/o: Uterus
• laryng/o: Larynx
• leuk/o: White
• men/o: Menstruation
• my/o: Muscle
• nephr/o: Kidney
• neur/o: Nerve
• opt/o: Vision
• orch/o: Testis, testicle
• pneum/o: Lungs
• thorac/o: Chest

See the following box for examples of common word roots in medical terms.

More on Combining Vowels

A combining vowel is placed to connect two word roots or to connect a word root and a suffix. However, a combining vowel should not be used to connect a prefix and a word root. Note that not all medical terms will have combining vowels. See guidelines on using combining vowels in Table 1.4a.

Table 1.4a. Guidelines on Combining Vowels