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Medical Terminology: Singular and Plural

Medical Terminology: Singular and Plural

11 Rules for Changing Singular Terms to Plural Terms

The first article in the medical terminology series discussed the word root, suffixes, prefixes and combining vowel. This article covers 11 rules for changing singular terms to plural terms. While building a medical vocabulary and combining and working with word parts, it is important to understand the rules for pluralization.

In the English language, a plural is formed by simply adding an -s to the singular term. However, there are some exceptions to this rule when a noun ends in -s, -sh, -ch, and some nouns that end in -o. These words are changed to plural by adding an -es. There are some additional rules for English terms but this article will focus on medical terms.

Because medical terms are derived from Latin and Greek terms, they do not always follow the normal rules for pluralization as English terms. These rules hold true in some instances but not all instances. There are always exceptions to these rules. Below are a few rules to remember when changing the singular form of medical terms to the plural form of medical terms.

 

Medical Terminology Rule #1: Words Ending in -a.

When the singular form of the word ends with -a, keep the -a and add an -e.

Axilla                     A pyramid-shaped space forming the underside of the shoulder.
Axillae

Pleura                   A delicate serous membrane enclosing the lung.
Pleurae

Conjunctiva         A mucous membrane lining the inner surface of the eyelid and anterior part of the sclera.
Conjunctivae

Vertebr              One of the bones of the spinal column.
Vertebrae

Scapula                One of the pairs of large flat triangular bones that forms the dorsal part of the shoulder.
Scapulae

Petechia               Numerous tiny purple or red spots appearing on the skin as a result of tiny hemorrhages.
Petechiae

 

Medical Terminology Rule #2: Words Ending in -ax.

When the singular form of the word ends with -ax, drop the -x and add -ces.

Thorax                  The upper part of the trunk that contains the rib cage, lungs some of the abdominal organs.
Thoraces

Pneumothorax     Air in the pleural space which causes the lung to collapse.
Pneumothoraces

 

Medical Terminology Rule #3: Words Ending in -ex.

When the singular form of the word ends with -ex, drop the -ex and add -ices.

Vortex                  A whirlpool effect caused by a spinning mass of fluid.
Vortices

Apex                     The top of the summit.
Apices

Cortex                   The outer layer of an organ.
Cortices

 

Medical Terminology Rule #4: Words ending in -is.

When the singular form of the word ends with -is, drop the -is and add -es

Metastasis           When a tumor cell moves from the primary location and establishes a remote location.
Metastases

Diagnosis             Identification of a disease or a condition
Diagnoses

Anastomosis       The connection between two vessels
Anastomoses

Prosthesis             An artificial device used to replace a missing body part.
Prostheses

 

Medical Terminology Rule #5: Word Ending in -ix.

When the singular form of the word ends with -ix, drop the -x and add -ces.

Cervix                   The part of the uterus that protrudes into the vagina.
Cervices

Appendi             An accessory part. The vermiform appendix is a process extending from the cecum.
Appendices

 

Medical Terminology Rule #6: Words ending in -ma.

When the singular form of the word ends with -ma, keep the -ma and add -ta.

Sarcoma               A malignant neoplasm of the soft tissue.
Sarcomata

Fibroma                Benign neoplasm made of connective tissue.
Fibromata

 

Medical Terminology Rule #7: Words ending with -on.

When a singular form of the word ends with -on, drop the -on and add -a.

Ganglion              A knotlike mass of nervous tissue.
Ganglia

Spermatozoon     A mature male germ cell.
Spermatozoa

 

Medical Terminology Rule #8: Words ending with -us.

When a singular form of the word ends with -us, drop the -us and add -i

Thrombus           An aggregation of platelets, fibrin and clotting factors. Is also known as a blood clot,
Thrombi

Bronchus             A air passage in the lung.
Bronchi

Alveolus               Tiny air sacs of the lung formed in clusters.
Alveoli

Embolus              A piece of a thrombus that travels in the bloodstream until it becomes lodged in a vessel.
Emboli

Calculus               An abnormal stone formed in the body usually found in the urinary tract.
Calculi

Bacillus                A rod-shaped bacteria.
Bacilli

 

Medical Terminology Rule #9: Word ending with -um.

When a singular form of the word ends with -um, drop the -um and add -a

Bacterium           A unicellular micro-organism.
Bacteria

Diverticulum      A pouchlike herniation through the muscular wall of an organ like the small intestine.
Diverticula

Atrium                 A chamber or cavity such as on the right and left side of the heart.
Atria

Ovum                   An egg.
Ova

 

Medical Terminology Rule #10: Words ending with -y.

When a singular form of the word ends with -y, drop the -y and add -ies.

Therap              The treatment of a disease or condition.
Therapies

Biopsy                  The removal of a small piece of living tissue for a microscopic examination to confirm or establish a diagnosis.
Biopsies

 

Medical Terminology Rules #11: Words ending with -x.

When a singular form of the word ends with -x, drop the -x and add -ges.

Laryn                The organ of voice.
Larynges

Meninx                The three membranes that enclose the brain and spinal cord.
Meninges

Phanlnx               Bones of the fingers and toes.
Phalanges

Hopefully, this article will give you some additional basic concepts of medical terms to assist you in building a medical vocabulary. As you acquire more basic skills you will increase your understanding of medical terminology.

 

For additional information on Medical Terminology read the article Medical Terminology Basics!

Medical Terminology Singular and Plural Infographic

 

Disclaimer: The information contained on this site is not intended or implied to be a substitution for professional medical advice, diagnosis or treatment. All content, including text, graphics, images, and information, contained is provided for educational purposes only. You assume full responsibility for how you chose to use this information.
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