Rules for Word Formation

1. Introduction to Word Formation

You have already learned how words are assembled using roots, prefixes, suffixes, and combining forms. Now you will learn about word formation rules. These rules are important because they will help you spell, pronounce, and interpret medical terms.

Understanding word formation rules aids in breaking down complex terminology into understandable parts. This helps healthcare professionals use medical terms fluently while avoiding miscommunication and errors.

Remember the general structure of medical terms:

• Prefix (optional) - Modifies the meaning of the root.
• Word root (required) - Provides a foundation for the term and defines the main subject.
• Combining vowel (optional) - Most commonly “o” and used to connect elements to make them easier to say.
• Suffix (required) - Describes the condition, disease, or procedure.

Here are some rules to follow.

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Rule 1: When to Use a Combining Vowel
Combining vowels are used between a root and a suffix if the suffix begins with a consonant.

The examples below show the correct use of combining vowels.

Used when the suffix begins with a consonant.
Nephr/o (kidney) + -logy (study of) → Nephrology

Not used when the suffix begins with a vowel.
Nephr/o + -itis (inflammation) → Nephritis (NOT Nephroitis)

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Rule 2: When to Keep a Combining Vowel Between Two Roots
Always retain the combining vowel when joining two roots.

The examples below show the use of a combining vowel between two roots (a multi-root word).

Gastr/o (stomach) + enter/o (intestine) + -logy (study of) → Gastroenterology

Cardo/o (heart) + my/o (muscle) + pathy (disease) → Cardiomyopathy

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Rule 3: Prefixes Are Always Attached Directly to the Root
Do not use a combining vowel between a prefix and a root.

The example shows that no combining vowel is used between a prefix and a root.

Hyper- (excessive) + tension (pressure) → Hypertension

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Rule 4: Changing Singular and Plural Forms
Realize that many medical terms change endings to form the plural. Make sure to appropriately change each term. You will learn more about this in another lesson.

MTA02

terms to know

Term	Definition	Audio
Bronchus	Large airways of the lungs (plural bronchi)	AUDIO
Appendix	Small, pouch-like structure attached to a larger pouch that opens to the large intestine near the junction with the small intestine (plural appendices)	AUDIO
Ganglion	Collection of nerve cell bodies in a specific part of the nervous system (plural ganglia)	AUDIO

2. Word Formation Using Prefixes, Roots, and Suffixes

As you have learned, words can be formed using prefixes, roots, and suffixes. Each of these word parts can be used in particular ways.

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Prefixes can be used to modify the meanings of words.

The examples below show how prefixes can provide different meanings associated with the same root word. Remember that prefixes often indicate number, position, direction, time, or negation.

Brady- (slow) + cardia (heart rate) → Bradycardia (slow heart rate)
Tacy- (fast, rapid) + cardia (heart rate) → Tachycardia (rapid heart rate)

Dys- (abnormal) + pnea (breathing) → Dyspnea (abnormal breathing, specifically difficulty or discomfort in breathing)
A- (without) + pnea (breathing) → Apnea (absence of breathing, such as pausing in breathing)

Poly- (many) + uria (urine condition) → Polyuria (excessive urination)
Hemat (blood) + uria (urine condition) → Hematuria (blood in urine)

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Remember that suffixes are used to describe a procedure, condition, or disease.

The examples below show how suffixes can be used in combination with word roots.

Arthr/o (joint) + -itis (inflammation) → Arthritis (joint inflammation)

Arthr/o (joint) + -scopy (visual examination) → Arthroscopy (viewing inside a joint)

Mast/o (breast) + -ectomy (surgical removal) → Mastectomy (breast removal)

Hem/o (blood) + -lysis (breakdown) → Hemolysis (destruction of red blood cells)

Bronch/o (respiratory passages) + pneumon (lung) + ia (condition or abnormal state) → bronchopneumonia (a disease of the respiratory passages and lungs)

You can also use both prefixes and suffixes with the same word root, as shown below.

Hyper- (excessive) + glyc (sugar) + emia (blood condition) → Hyperglycemia

Hypo- (below or deficient) + glyc (sugar) + -emia (blood condition) → Hypoglycemia

Peri- (around) + card (heart) += itis (inflammation) → Pericarditis (inflammation of the pericardium, a membrane around the heart

terms to know

Term	Definition	Audio
Bradycardia	Slow heart rate	AUDIO
Tachycardia	Rapid heart rate	AUDIO
Dyspnea	Abnormal breathing (difficulty or discomfort in breathing)	AUDIO
Apnea	Absence of breathing	AUDIO
Hematuria	Blood in urine	AUDIO
Hemolysis	Destruction (bursting) of red blood cells	AUDIO
Hyperglycemia	High blood sugar	AUDIO
Pericarditis	Inflammation of the membrane around the heart	AUDIO

FLASHCARD SET 1.1.2_2

3. Pitfalls and Examples

Although word formation becomes straightforward with practice, it is important to watch for common errors. This section focuses on common errors and sources of confusion.

For example, it is important to pay attention to the use of combining vowels and to follow the rules provided in this and another lesson

Here is an incorrect example. Mistakenly adding a combining vowel when combining the word root gastr (stomach) with the suffix –itis (inflammation) produces the word gastroitis, which is incorrect. Remember the rule: When connecting a word root and a suffix, a combining vowel is usually NOT USED if the suffix begins with a vowel. The correct term is gastritis (stomach inflammation), which lacks the combining vowel.

try it

Now let’s try another example. Try producing a word using the word root card (heart) and the suffix –algia (pain).

Write the word with and without a combining vowel and decide which word is correct.

The correct word is cardialgia, which means pain in the area of the heart. The incorrect word is cardioalgia.

Another problem is that words are sometimes very similar. Pay particular attention to distinguishing these terms when you study. You may want to pair them in your study resources to make certain that you note the difference.

If you notice that a word is similar to another word, you may want to note the similar word with your definition to remember to distinguish the two terms.

EXAMPLE

Ileum (part of the small intestine) vs. Ilium (hip bone).

Prostate (male gland) vs. Prostrate (lying flat or weak).

Laryngectomy (removal of the larynx) vs. Laryngostomy (creation of a laryngeal opening).

Pay close attention to note others that you encounter.

terms to know

Term	Definition	Audio
Ileum	Part of the small intestine	AUDIO
Ilium	Hip bone	AUDIO
Prostate	A male gland	AUDIO
Prostrate	Lying flat or weak	AUDIO

FLASHCARD SET 1.1.2_3