How to decode a word from its roots, prefixes and suffixes
TEAS 7 outline: Determine word meaning from word parts (roots, prefixes, suffixes)
Also covers HESI A2 Vocabulary (Word parts)
- Many health words are built from a prefix, root and suffix.
- The root carries the core meaning: cardi- means heart.
- A prefix changes the meaning: brady- means slow.
- A suffix names the kind of thing: -itis means inflammation.
- To decode a word, split it, define each part, then combine.
Key facts
- A prefix comes before the root and modifies its meaning, often telling location, amount or speed; a suffix comes after the root and also changes the meaning.
- A combining vowel, usually o, joins parts for easier pronunciation, as in cardio- and hepato-.
- Body-part roots: cardi- heart, hepat- liver, gastr- stomach, nephr- and ren- kidney, neur- nerve, oste- bone, derm- skin, hem- and hemat- blood.
Show all 7 key factsShow fewer
- Opposite prefixes: hypo- under or deficient vs. hyper- above or excessive; brady- slow vs. tachy- fast; pre- before vs. post- after.
- Procedure suffixes: -ectomy removal, -otomy incision (cutting into), -ostomy making an opening.
- Condition suffixes: -itis inflammation, -megaly enlargement, -emia blood condition, -pathy disease; -ology means the study of a subject.
- To decode, find the suffix, then the prefix, then the root, and check that the combined meaning fits the sentence.
Quick check1 question · 2 more at the end
A health brochure explains hepatitis. Using the word parts hepat- and -itis, what does hepatitis mean?
Correct answer: B.
The root hepat- means liver, and the suffix -itis means inflammation, so hepatitis is inflammation of the liver. To decode a medical term, define the suffix first (what kind of condition), then the root (which body part). Enlargement would be -megaly, removal would be -ectomy, and the kidney root is nephr- or ren-.
A Enlargement is the suffix -megaly (as in hepatomegaly), not -itis.
B Correct: hepat- means liver and -itis means inflammation.
C Surgical removal is the suffix -ectomy, not -itis.
D The kidney root is nephr- or ren-; hepat- refers to the liver.
Full lesson
Each part starts with its main idea. Open a part when you want the details.
The short answer: Many health and science words are built from three kinds of parts. The root carries the core meaning (cardi- = heart), a prefix at the front changes it (brady- = slow), and a suffix at the end tells what kind of thing it is (-itis = inflammation). To decode a word, split it, define each part, and combine the meanings.
1 How are health and science words built?Most long science words are a few short parts joined together like building blocks. 1 min
Most long science words are a few short parts joined together like building blocks. Learn the parts once and you can read words you have never seen.
| Part | Where it sits | Its job | Example |
|---|---|---|---|
| Prefix | Front | Changes the meaning: where, how much, how fast, when | pericardium (around) |
| Root | Middle | Core meaning, often a body part | pericardium (heart) |
| Suffix | End | What kind of thing: condition, procedure, field | pericarditis (inflammation) |
A combining vowel, usually o, makes words easier to say: cardi + o + logy = cardiology. Some words have two roots and no prefix at all.
2 Which word parts are most useful to know?A small set of common word parts unlocks many health and science terms. 1 min
A small set of common word parts unlocks many health and science terms. Start with these.
| Roots | Prefixes | Suffixes |
|---|---|---|
| cardi- heart | hypo- under, deficient | -itis inflammation |
| hepat- liver | hyper- above, excessive | -ectomy removal |
| gastr- stomach | brady- slow | -otomy incision |
| nephr-, ren- kidney | tachy- fast | -ostomy opening |
| neur- nerve | pre- before | -megaly enlargement |
| oste- bone | post- after | -emia blood condition |
| derm- skin | peri- around | -pathy disease |
| hem-, hemat- blood | endo- within | -ology study of |
3 How do you decode a word you have never seen?Split the word into parts, define each part, then join the meanings. 1 min
Split the word into parts, define each part, then join the meanings. Use the same four steps every time.
- Find the suffix. It tells you the category: a disease, a procedure, a field of study.
- Find the prefix. It tells you where, how much or how fast.
- Find the root. It names the body part or topic.
- Combine and check. Say "suffix of prefix-root," then make sure it fits the sentence.
Example text: After a long run in the heat, Malia's watch flagged tachycardia. She had skipped breakfast, so the nurse also checked for hypoglycemia.
- tachycardia = tachy- (fast) + cardi (heart) → a fast heart rate.
- hypoglycemia = hypo- (under) + glyc (sugar) + -emia (blood condition) → low blood sugar.
The context agrees with both readings: running in the heat fits a fast heart rate, and skipping breakfast fits low sugar.
4 Which look-alike parts cause the most mistakes?Look-alike and opposite word parts are easy to mix up, so slow down here. 1 min
Look-alike and opposite word parts are easy to mix up, so slow down here. Each rule below has a correct and an incorrect use.
| Rule | Correct | Incorrect |
|---|---|---|
| hypo- = under; hyper- = over | Hyperglycemia means high blood sugar. | Hypoglycemia means high blood sugar. |
| brady- = slow; tachy- = fast | Bradycardia is a slow heart rate. | Bradycardia is a racing heart rate. |
| -ectomy = removal; -otomy = cutting into | A gastrectomy removes all or part of the stomach. | A gastrotomy removes the stomach. |
| peri- = around; endo- = within | Pericarditis affects the covering around the heart. | Pericarditis affects the heart's inner lining. |
| -itis = inflammation; -megaly = enlargement | Hepatitis is inflammation of the liver. | Hepatitis is an enlarged liver. |
Quick test: what does nephrectomy mean? (Removal of a kidney: nephr- kidney + -ectomy removal.)
Common mistakes
The traps students fall into most. Read these before you practice.
Watch out: Hypo- means under or too little, not too much; hypoglycemia is low blood sugar and hyperglycemia is high blood sugar.
Watch out: Brady- means slow and tachy- means fast, not the other way around.
Watch out: -ectomy means removal, not just cutting into; cutting into is -otomy and making an opening is -ostomy.
Watch out: -itis means inflammation, not infection or enlargement; enlargement is -megaly.
Watch out: Peri- means around and endo- means within, so pericarditis is inflammation around the heart, not inside it.
How to remember it
Link each tricky part to an everyday word. A car's tachometer measures how fast the engine turns (tachy- = fast), and a hyperactive child has too much energy (hyper- = excessive).
Self-check:
- Split neuropathy into parts and define it.
- Explain the difference between a gastrotomy and a gastrostomy.
- Name the prefix that is the opposite of pre-.
Show answers
- Neur + o + -pathy = disease of the nerves.
- neur- = nerve (the root).
- o = the combining vowel.
- -pathy = disease (the suffix).
- A gastrotomy cuts into the stomach; a gastrostomy makes an opening.
- Both share the root gastr- (stomach).
- -otomy = incision, so a gastrotomy is a cut into the stomach.
- -ostomy = opening, so a gastrostomy is an opening into the stomach.
- Post-.
- pre- means before; post- means after.