Hypo vs. Hyper: What’s the Difference?

English has a lot of confusing words that mix up writers from time to time. Many of these words sound the same or are spelled the same or their definitions are so similar that it’s hard to tell them apart.

Thankfully, this isn’t the case with the two prefixes hypo vs. hyper. While they do have similar sounds, both starting with “hyp,” they have the exact opposite meanings. Since their meanings are so different, it’s that much more important that we be careful not to mix them up in our writing.

What is the Difference Between Hypo and Hyper?

In this post, I want to discuss the differences between hypo and hyper. I will go over their definitions, their uses inside a sentence, and provide a few ways to tell them apart.

After reading this post, you shouldn’t ever mix up these two words again.

When to Use the Prefix Hypo

hypo versus hypo grammar rulesThe prefix hypo means below, beneath, under; less than normal, deficient; in the lowest state of oxidation.

  • The doctor used a hypodermic needle to draw blood. (Beneath the skin)
  • We bought a hypoallergenic baby blanket at the store. (Less likely to provoke an allergic reaction)
  • The doctor diagnosed me with hypoglycemia. (Lower than normal glucose in blood.

Hypo comes from the Greek word hupo, which translates as under, so it has carried over much of the same original Greek meaning into modern English.

The meaning of hypo, as well as hyper, is relevant in many cases to medical conditions. For example, hypochondria, hypothyroidism, hypoacidity, hypocalemia, hypothermia, etc. All of these have to do with having less than or under the normal or recommended amount of something.

When to Use the Prefix Hyper

Hyper prefix meaning and hypo meaningThe prefix hyper means over, above, beyond; excessive, excessively.

  • The plane was so fast it was hypersonic. (Five times beyond the speed of sound)
  • What are you working on? You have been hyperactive lately. (Excessively active)
  • These documents are hypercritical to the safety of the region. (Excessively important)

Hyper comes from the Greek word huper, which translates as over, beyond. As is the case with the definition of hypo, hyper has maintained its original Greek meaning in modern English.

Hyper also accompanies many medical conditions, hypertension, hyperthyroidism, hyperesthesia, hyperacidity, etc.

Remember the Difference

Hyper prefix versus hypo prefix definitionAs you can see, when you define hyper and you define hypo, they essentially have the opposite meanings of each other, so it’s that much more important that we keep the separated in our writing.

Luckily, there is an easy trick to keep track of hyper vs. hypo.

Hypo means below normal. Hypo and below both have the letter “O” in them.

Hyper means excessive or extremely. Hyper, excessive, and extremely all have the letter “E” in them.

If you can remember this simple trick, you shouldn’t ever mix up the meanings of hypo and hyper again.


Although these words have similar sounds, they are nearly opposite meanings. A careful writer always observers the distinction between these two prefixes.

The prefix hypo means below normal, under.

The prefix hyper means above, beyond, excessive.

Both come from Greek words and are widely used in the medical field.