Medical Prefixes to Indicate Amount

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next: Time & Negation in Medical Prefixes

You're on a roll. Keep up the good work!

Take Quiz Watch Next Lesson
Your next lesson will play in 10 seconds
  • 0:33 Prefixes Indicating Number
  • 3:11 High and Low
  • 3:49 Too Fast and Slow
  • 4:25 Few and Many
  • 5:34 Half
  • 6:28 Lesson Summary
Save Save Save

Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course.

Log in or Sign up

Speed Speed

Recommended Lessons and Courses for You

Lesson Transcript
Instructor: Adrianne Baron

Adrianne has taught high school and college biology and has a master's degree in cancer biology.

This lesson will cover the prefixes that are used to define amounts in medical terminology. We will study these prefixes by looking at ones with the same meaning and opposite meaning.


A prefix is a word part that helps to specify the meaning of a medical term. There are many ways that prefixes do this. Some prefixes specify the subject of the medical term by telling the size, location, position, time and amount. It is important to remember that not all medical terms have prefixes. When it is present, the prefix is found at the beginning of the medical term. We are now going to explore the prefixes that indicate amounts.

Prefixes Indicating Number

You may not realize that you already know some of the prefixes that indicate numbers. If you go back, or for some people go way back, in your memory, you may recall riding a tricycle when you were a young child. You may also recall that you eventually got to the point of riding a bicycle. Perhaps you recall going to the circus and seeing a person riding a unicycle. Other than the height of the cycle, what was the other main difference?

The difference was in the number of wheels. The tricycle had three wheels, while the bicycle had two wheels and the unicycle had one wheel. You notice that the words are the same with the exception of the prefix, which specified the number of wheels. This is exactly the same way the number prefixes work in medical terminology.

The prefix 'uni-' means 'one.' This appears in terms like 'unilateral,' which means 'one side.' For instance, 'unilateral vision' means 'vision in one eye.' The prefix 'mono-' also means 'one.' 'Mono-' is used in terms such as 'mononucleosis.' This disease got its name because immune cells with 'one nucleus' are the ones that respond in the body to fight the disease.

The prefix 'bi-' means 'two.' 'Bi-' appears in medical terms like 'bilateral' and 'biceps.' 'Bilateral' means 'two sides.' An example of how this is used in healthcare is 'bilateral stroke,' meaning 'stroke affecting both sides of the brain.' 'Biceps' is the term used to describe the muscle on the front side of the upper arm. The muscle has 'two heads,' which is the exact meaning of 'biceps.'

Another prefix meaning 'two' is 'di-.' 'Dimorphic' is a term that uses this prefix and means 'two forms.' This can refer to the fungi that can infect the body. It is sometimes in mold form and other times in yeast form. 'Bi-' and 'di-' can be used interchangeably.

The prefix 'tri-' means 'three.' 'Tri-' appears in terms like 'tricuspid.' The term 'tricuspid' is used for the teeth in your mouth or the valve in your heart that has 'three cusps.'

There is another prefix that denotes a number. 'Quadri-' means 'four.' This prefix is most commonly seen in the term 'quadriplegic.' This term means 'paralysis in all four limbs.' The quadriceps got their name using this prefix. 'Quadriceps' means 'four heads,' referring to the four heads that make up this muscle.

High and Low

With all the concern in recent years about high blood pressure, you are probably familiar with the term 'hypertension.' This term is formed using the prefix 'hyper-,' meaning 'high or excessive.' 'Hypertension' means 'high tension or pressure,' which refers to the pressure in the blood vessels.

A person that has diabetes may sometimes experience a condition of being hypoglycemic. The prefix 'hypo-' means 'low.' 'Hypoglycemic' means 'low blood glucose.' 'Hypothermia' is a term used to describe a 'low body temperature.'

Too Fast and Slow

There are times when you may want to explain that something is happening faster or slower than it normally should. For instance, a person may have a heart rate that is faster than it should be. The term we use for this is 'tachycardia.' This uses the prefix 'tachy-,' which means 'fast or faster than normal.'

On the other hand, you may need to explain that something is happening very slow or slower than normal. The prefix we use for this is 'brady-.' To describe 'slower than normal breathing,' you would use the term 'bradypnea.'

To unlock this lesson you must be a Member.
Create your account

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use

Become a member and start learning now.
Become a Member  Back
What teachers are saying about
Try it risk-free for 30 days

Earning College Credit

Did you know… We have over 200 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Create an account to start this course today
Try it risk-free for 30 days!
Create an account