Hypo vs. hyper?

Words with the prefix hypo mean ‘below normal,’ ‘beneath,’ or ‘under.’ The prefix and adjective hyper means ‘excessively,’ ‘above normal,’ or ‘hyperactive.’

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What is the difference between hypo and hyper?

The words hypo and hyper sound and look similar, but they are actually opposite terms. As prefixes, hyper- appears in words that describe something as ‘above,’ ‘excessive,’ or ‘beyond normal.’ Meanwhile, the prefix hypo- conveys the meaning of  ‘under’ or ‘below normal.’ 

The words “hypo” and “hyper” also occur as abbreviations for terms like “hyperactive” or “hypodermic,” but most words with the prefixes (abbreviated or not) retain an element of their original sense. 

What does hypo mean?

The prefix hypo- describes something as ‘under,’ ‘beneath,’ or ‘below normal,’ and often occurs in terms like “hypoglycemia” (‘abnormally low blood-glucose levels’) or “hypodermic” (‘beneath the skin’). Additional examples include: 

  • Hypothyroidism (n.): ‘when the thyroid gland is unable to produce thyroid hormones.’
  • Hypochromia (n.): ‘a lack of color or pigmentation.’ 
  • Hypoplasia (n.): ‘defective or incomplete development (especially of an organ)
  • Hypodermis (n.): ‘the tissue found directly under the epidermis (subcutaneous fascia).’ 

English speakers may also write “hypo” as an abbreviated noun (for terms containing the prefix), or with nouns to describe anything that is ‘under,’ ‘below,’ ‘slow,’ or ‘deficient’ (“Hypo” 857). 

Sentence examples:

  • “Like me, a fellow hypo may suffer from unexplained weight gain.” — The Guardian 
  • “Early-generation transgenic mice, while very productive, lack native B-cell signaling… and therefore are often ‘hypo-responders’ to certain antigens/immunizations.” — Forbes

What does hyper mean?

The prefix hyper- describes something as ‘excessive,’ ‘over,’ ‘above,’ or ‘beyond normal.’ For example, the prefix appears in terms like “hyperventilate” (‘to breathe too quickly and over-oxygenate blood’) and “hypertension” (‘to have excessively high blood pressure’).  

Additional example with the prefix hyper- include: 

  • Hyperspace (n.): ‘a space with more than three dimensions.
  • Hypertext (n.): ‘to be organized or linked in a non-sequential manner.’ 
  • Hypercritical (adj.): ‘to be excessively critical.’ 
  • Hypertonic (adj.): ‘having greater osmotic pressure of two aqueous solutions’ or; ‘characterized by excessive tension.’
  • Hyperosmia (n.): ‘an acute sense of smell.’

The prefix hyper- also occurs in the adjective “hyperactive” (‘excessively active’), which we can abbreviate as “hyper” to mean ‘excitable,’ ‘high-strung,’ ‘emotionally stimulated,’ or simply ‘excessive’ (hyphens may be necessary). 

Sentence examples:

  • “Karate is where you put hyper kids when you’re not ready to put them on medication.” — The New York Times
  • “If you feel like you just can’t relax, your thyroid may be “hyper.’” — Health
  • “One Sunday evening in 2020, I was walking from my car to a friend’s house in the hyper-hipster corner of Hauz Khas in New Delhi…” — Vogue India
  • “This is because cytokines can, if they are overproduced, lead to hyper-inflammation, an immune system response that sometimes proves fatal.” — The Independent 

Synonyms of hyper

[Adj.] Crazy, energetic, excitable, flighty, fluttery, high-strung, hysterical, insane, jittery, jumpy, lively, manic, nervous, overexcited, skittish, spasmodic, spirited, tireless, untiring, wild. 

Antonyms of hyper

[Adj.] Calm, collected, composed, cool, dull, easygoing, enerving, imperturbable, nerveless, unexcitable, unflappable, unshakable, unstimulating. 

Origins of hyper and hypo

According to the New Oxford English Dictionary, the prefixes hypo- and hyper- originate from Greek, where huper- (hyper) means ‘over, beyond’ and hupo- (hypo) means ‘under, beneath’ (857). 

How to remember the difference between hyper and hypo?

To remember the difference between “hyper” and “hypo,” associate the letter “o” of “hypo” with the word “low.” For instance, if you use a “hypoallergenic” shampoo, that means your product contains low amounts of allergens (or lower than standard). 

Remembering “hyper” is a bit easier if you associate it with feeling over-stimulated or energetic. In either case, there’s an abundance of energy, so when “hyper” pops-up in a term, you know it’s describing something excessive. 

In summary: 

  • Hypo-” => o => “low” or “below normal”
  • Hyper-” => “overly-energized” or “in abundance” => “excessive” 

Commonly confused terms: hypothyroidism vs. hyperthyroidism

Hyperthyroidism” and “hypothyroidism” are healthcare terms that are very easy to confuse. Both thyroid disorders can cause goiters, fatigue, sleep disturbances, and weight changes. But what’s more confusing is how either condition can arise from an autoimmune disease or a genetic predisposition (including environmental triggers or genetic mutations). So, how are they different?  

As paraphrased from Melloni’s Pocket Medical Dictionary (MPMD), hyperthyroidism is a condition caused by excessive hormone production or ingestion of thyroxine (thyroid hormone). Common symptoms of hyperthyroidism include weight loss, rapid heart rate, tremors, increased bowel movement, and sensitivity to heat (209). 

Hypothyroidism is the opposite of hyperthyroidism because it’s a condition caused by low thyroxine production (213). The symptoms of hypothyroidism also follow an inverse pattern to hyperthyroidism, such as a slower rate of metabolism (i.e., weight gain), lower heart rate, sensitivity to cold, constipation, thinning hair, and more. 

Causes of hypothyroidism vs. hypothyroidism

There’s also a big difference between what causes hypothyroidism versus hyperthyroidism. For instance, Grave’s disease is the most common cause of hyperthyroidism, although it can also occur from thyroiditis (‘inflammation of the thyroid’) or hyperfunctioning thyroid nodules.

In contrast, the onset of hypothyroidism can occur from Hashimoto’s thyroiditis, hyperthyroid treatments (e.g., radioactive iodine or levothyroxine), thyroid surgery, radiation therapy, medications, or even other autoimmune illnesses. Iodine deficiency, pregnancy, congenital diseases, or issues with the pituitary gland are less common sources of hypothyroidism.

How to use hypothyroidism and hyperthyroidism in a sentence?

If you’re interested in learning more about hypo- or hyperthyroidism, it’s best to seek medical advice from a doctor–– not a grammarian. But if you need a few leads on how to use these terms in a sentence, we’ve got you covered. 

*P.S.: We highly recommend reading the American Thyroid Association’s informative brochures about different thyroid disorders and treatments

Sentence examples:

  • “When the thyroid gland malfunctions, it either produces too much thyroid hormone leading to hyperthyroidism or too little thyroid hormone, leading to hypothyroidism.” — Irish Times
  • “Model Gigi Hadid revealed on Twitter that she has an autoimmune disorder, Hashimoto’s disease, which is the most common cause of hypothyroidism.” — Today 
  • “The autoimmune disorder, in which one’s immune system attacks the thyroid, is the most common cause of hyperthyroidism in the U.S. …” – The New York Daily News

Looking for more health-related topics?

If you enjoy learning the grammatical nuances of the healthcare terminology, check out the following articles from The Word Counter

FAQ: Related to hypo vs. hyper

Does the word “hypochondria” use the prefix hypo-?

The prefix hypo- is, in fact, found in the word hypochondria, which Lexico defines as  “[an] abnormal anxiety about one’s health, especially with an unwarranted fear that one has a serious disease.” The noun’s meaning departs from our traditional understanding of hypo-, where Greek hupo- means ‘under.’ 

However, the noun “hypochondria” actually originated from Greek hupokhondria, meaning ‘under the sternal cartilage.’ The theory behind the term is fairly ironic, as the meaning stems from the belief that a hypochondriac’s anxiety arose from their liver and spleen. 

Test Yourself!

Test how well you understand the difference between hyper and hypo with the following multiple-choice questions. 

  1. True or false: “Hyper” is an abbreviation for the adjective “hyperactive.”
    a. True
    b. False 
  2. The word hyper is a ______________.
    a. Prefix
    b. Noun
    c. Adjective
    d. A and C
  3. The prefix hypo- describes something as ____________.
    a. Beneath 
    b. Under
    c. Below normal
    d. All of the above
  4. Which of the following is not synonymous with the adjective hyper?  
    a. Flighty
    b. Hyperactive
    c. Enerving
    d. Untiring
  5. Hyper- originates from which Greek term? 
    a. Huper-
    b. Apo- 
    c. Hupo-
    d. Pro-
  6. Bonus: The presence of high thyroid-stimulating hormone (TSH) and low thyroxine (thyroid hormone) may indicate ___________. 
    a. Hyperthyroidism 
    b. Hypothyroidism 
    c. Healthy thyroid function 
    d. A and B


  1. A
  2. D
  3. D
  4. C
  5. A
  6. B


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  3. Ellen, B. “Weigh your words before mocking the overweight.” The Guardian, TheGuardian.com, 2 Jan 2016.
  4. Hutto, S. “I Explain All the Sports.” The New York Times, NYTimes.com, 1 Feb 2019. 
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  6. Hyper.” The Merriam-Webster.com Dictionary, Merriam-Webster Inc., 2021.
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  9. Hyperglycemia.”Lexico, Oxford University Press, 2021.
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  11. Hypertension.” Lexico, Oxford University Press, 2021.
  12. Hyperventilate.” Cambridge Dictionary, Cambridge University Press, 2021.
  13. Hypo.” The Merriam-Webster.com Dictionary, Merriam-Webster Inc., 2021.
  14. “Hypo.” The New Oxford American Dictionary, 3rd ed., Oxford University Press, 2010, p. 857.
  15. Hypochondria.” Lexico, Oxford University Press, 2021.
  16. Hypochromia.” The Merriam-Webster.com Dictionary, Merriam-Webster Inc., 2021.
  17. Krueger, A. “19 Thyroid Disease Symptoms You Should Get Checked Out ASAP.“ Health, Health.com, 9 Sept 2019. 
  18. Machalinski, A. “’I couldn’t get out of bed’: These are the signs of a thyroid disorder.” Today, Today.com, 18 Nov 2016. 
  19. Mohney, G. “Scientists Developing Hypo-Allergenic Apples.” ABC News, ABCNews.go.com, 21 Mar 2013.
  20. Mayo Clinic Staff. “Hyperthyroidism (overactive thyroid).” Mayo Clinic, MayoClinic.org, 2021. 
  21. Mayo Clinic Staff. “Hypothyroidism (underactive thyroid).” Mayo Clinic, MayoClinic.org, 2021. 
  22. Melloni, J.L., et al. “Hyperthyroidism;” “Hypothyroidism.” Melloni’s Pocket Medical Dictionary: Illustrated, Parthenon Publishing, 2004, pp. 209––213. 
  23. Nagarajan, A. “What we need to learn about fat acceptance.” Vogue India, Vogue.in, 28 Jan 2021. 
  24. Sullivan, R. “Blood test could help predict which Covid-19 patients are at greatest risk of critical illness.” The Independent, Independent.co.uk, 14 Oct 2020. Thompson, S. “The key to the endocrine system.” The Irish Times, IrishTimes.com, 19 Feb 2013.