150 Longest Long Words in English (+ Definitions)

This is the ultimate list of the 150 longest long words in the English language.

If you’re here, you either have an undying love for polysyllabic monstrosities or you’ve simply lost a bet and now need to know what “antidisestablishmentarianism” means. Either way, you’re in for a wild ride.

What Are Long Words Anyway?

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Road, forest, mountains -- Longest Words
I made this image with AI — Longest Words

Let’s get one thing straight: a long word isn’t just something that takes up half your notepad when you try to write it.

These are the tongue-twisters, the 12+ letter juggernauts, and the beasts that make spelling bees fun to watch but terrifying to compete in.

In technical terms, long words are “polysyllabic” – meaning they have many syllables.

They also make you sound at least 35% smarter when you use them in conversation.

Why Do Long Words Exist?

You might think these words exist purely to torture people who try to spell them (thanks, English language), but long words actually serve a purpose. Sometimes, a big word can sum up an idea that would otherwise need an entire sentence.

Other times, people just like showing off.

150 Longest Long Words in English (with Definitions)

Now, for what you came for – the 150 longest words, ranked from “that’s a mouthful” to “I’d need a week to say that.”

You’ve been warned.

The Classics

The words that have been torturing spelling bee contestants for decades.

  1. Antidisestablishmentarianism (28) – Opposition to the disestablishment of the Church of England.
  2. Floccinaucinihilipilification (29) – The act of deeming something worthless.
  3. Pneumonoultramicroscopicsilicovolcanoconiosis (45) – A lung disease caused by inhaling fine silicate or quartz dust.
  4. Hippopotomonstrosesquipedaliophobia (35) – Ironically, the fear of long words.
  5. Supercalifragilisticexpialidocious (34) – Fictional word made famous by Mary Poppins.
  6. Honorificabilitudinitatibus (27) – The state of being able to achieve honors.
  7. Incomprehensibilities (21) – The quality of being impossible to understand.
  8. Disproportionableness (21) – The state of being out of proportion.
  9. Uncharacteristically (20) – Not typically representative of one’s character.
  10. Inconsequentialities (20) – Things that are of little importance.

Medical Marvels

Words that make going to the doctor even scarier.

  1. Electroencephalographically (27) – Relating to brain wave recording.
  2. Otorhinolaryngologist (21) – Ear, nose, and throat doctor.
  3. Cardiothoracicvascularization (29) – Heart and lung surgery.
  4. Immunoelectrophoretically (25) – Relating to the electrical separation of molecules.
  5. Psychophysicotherapeutics (25) – The treatment of mental and physical disorders.
  6. Pseudopseudohypoparathyroidism (30) – A rare inherited disorder that simulates hypoparathyroidism.
  7. Thyroparathyroidectomized (25) – Having had the thyroid and parathyroid glands removed.
  8. Hematospectrophotometrically (28) – Related to the measurement of blood light absorption.
  9. Esophagogastroduodenoscopy (26) – A diagnostic procedure examining the esophagus, stomach, and duodenum.
  10. Lymphangioleiomyomatosis (24) – A rare lung disease that affects women of childbearing age.

Scientific Stunners

These words exist where chemistry meets spelling nightmares.

  1. Methionylthreonylthreonylglutaminylarginyl (42) – A component of a protein’s chemical name.
  2. Dimethylaminophenyltrimethylpyrazoline (38) – A chemical compound.
  3. Dichlorodifluoromethane (23) – A refrigerant gas.
  4. Tetrakishexahexaheptane (23) – A type of chemical compound.
  5. Hexakosioihexekontahexaphobia (29) – Fear of the number 666.
  6. Tetramethylethylene (19) – A hydrocarbon molecule.
  7. Sphygmomanometrically (21) – Related to measuring blood pressure.
  8. Anthropomorphologically (23) – Relating to attributing human traits to objects or animals.
  9. Spectrophotometrically (22) – Relating to the measurement of light spectra.
  10. Xenotransplantation (19) – Transplanting organs from one species to another.

Words You’ll Probably Never Use

These long words are perfect for impressing people at dinner parties or annoying your friends.

  1. Insubstantialities (18) – Things that lack substance.
  2. Counterrevolutionaries (22) – People who oppose a revolution.
  3. Overintellectualization (23) – Analyzing something too much.
  4. Disenfranchisement (18) – The act of depriving someone of the right to vote.
  5. Thermochromatography (20) – A process of separating compounds by temperature.
  6. Unconstitutionality (19) – The state of being unconstitutional.
  7. Hyperventilation (16) – Breathing too fast, leading to excess oxygen.
  8. Uncopyrightables (16) – Things that cannot be copyrighted.
  9. Deinstitutionalization (22) – The process of disbanding an institution.
  10. Anthropomorphization (20) – The process of giving human traits to non-humans.

Fun to Say (But Not to Spell)

Here are words that will impress your English teacher (and likely no one else).

  1. Magniloquent (12) – Speaking in a lofty or grandiose style.
  2. Sesquipedalianism (17) – The use of long words.
  3. Perspicaciousness (17) – The quality of having insight.
  4. Circumlocutionary (17) – Using too many words to express something.
  5. Obfuscatory (11) – Intentionally making something unclear.
  6. Pulchritudinous (15) – Physically beautiful.
  7. Acrimoniously (13) – Speaking or acting with bitterness.
  8. Idiosyncratically (17) – Relating to an individual’s unique mannerisms.
  9. Quizzicality (12) – A puzzled or questioning attitude.
  10. Unobjectionable (15) – Unable to be objected to.

Advanced Vocabulary

These long words will level up your Scrabble game with language jawbreakers.

  1. Antitransubstantiationalist (27) – Opposed to transubstantiation.
  2. Uncontradictorily (17) – Without contradiction.
  3. Thermodynamically (17) – Relating to the science of heat and energy.
  4. Irreconcilabilities (19) – Things that cannot be made compatible.
  5. Gastroenterologically (21) – Relating to the digestive system.
  6. Uninterchangeably (17) – Not capable of being exchanged.
  7. Ultramicroscopically (20) – On a very small scale.
  8. Compartmentalization (20) – The act of dividing into sections.
  9. Subcontrariety (14) – The relation of being subcontrary.
  10. Paleomagnetism (14) – The study of Earth’s ancient magnetic field.

The Rest of the Best

The grand finale of long words that you’ll probably never need—unless you’re in a spelling bee.

  1. Unobjectionably (15) – Without objection.
  2. Misinterpretation (17) – An incorrect understanding.
  3. Overimaginative (15) – Having too much imagination.
  4. Unfathomability (15) – The quality of being incomprehensible.
  5. Preponderantly (14) – In greater number or amount.
  6. Overcapitalization (18) – Too much investment in capital.
  7. Supernaturalism (15) – Belief in supernatural forces.
  8. Uncontrollability (17) – Not able to be controlled.
  9. Unceremoniously (15) – In a rough or abrupt manner.
  10. Electromagnetism (16) – The science of magnetic fields and electricity.
  11. Unsuccessfulness (16) – The state of being unsuccessful.
  12. Misunderstanding (16) – A failure to understand something correctly.
  13. Nonrepresentational (19) – Not representing real-world things.
  14. Hyperventilating (16) – Breathing too fast.
  15. Psychotherapeutically (21) – Relating to therapy for mental disorders.
  16. Miscommunication (16) – Failure to communicate effectively.
  17. Nontransferability (18) – Not able to be transferred.
  18. Incommunicatively (17) – Not able to communicate.
  19. Irreplaceableness (17) – Not able to be replaced.
  20. Disillusionment (15) – The feeling of being let down.
  21. Hypochondriacally (17) – In a manner relating to excessive health anxiety.
  22. Inaccessibility (15) – The quality of being difficult to reach or access.
  23. Uncharacteristic (16) – Not typical or usual for someone or something.
  24. Reconceptualization (19) – The act of rethinking a concept or idea.
  25. Institutionalization (20) – The process of establishing something as a norm.
  26. Irresponsibility (16) – The state of lacking responsibility.
  27. Unquestionability (17) – Not able to be questioned or doubted.
  28. Intercontinental (16) – Between continents.
  29. Hyperconsciousness (18) – An excessive awareness of oneself or one’s environment.
  30. Disproportionality (18) – The state of being out of proportion.
  31. Uncompartmentalized (19) – Not divided into sections.
  32. Irretrievableness (17) – The state of being unable to recover.
  33. Constitutionality (17) – Whether something is in accordance with the constitution.
  34. Underrepresentative (19) – Not fully or properly represented.
  35. Inappropriateness (17) – The quality of being unsuitable or improper.
  36. Photosynthesizing (17) – The process by which plants convert light into energy.
  37. Antiferromagnetism (18) – A type of magnetism where adjacent ions spin in opposite directions.
  38. Misinterpretations (18) – Multiple incorrect understandings of something.
  39. Microminiaturization (20) – The process of making something very small.
  40. Inapplicabilities (17) – The state of not being applicable.
  41. Oversimplification (18) – The process of making something simpler than it actually is.
  42. Electrocardiography (19) – The measurement and recording of electrical activity in the heart.
  43. Hypercholesterolemia (20) – The condition of having high levels of cholesterol in the blood.
  44. Constitutionalizing (19) – The act of establishing or giving something a constitution.
  45. Extraterrestrialism (19) – Belief in or the existence of life beyond Earth.
  46. Thermoregulation (16) – The process of maintaining a stable body temperature.
  47. Interrelationship (17) – A mutual relationship between two or more things.
  48. Nonrepresentatives (18) – Things or people that do not represent something.
  49. Electromagnetically (19) – Relating to electromagnetism.
  50. Counterintuitively (18) – In a manner that goes against intuition.
  51. Individualistically (19) – In a way that emphasizes individual rights or qualities.
  52. Uncommunicativeness (19) – The quality of being unwilling or unable to communicate.
  53. Reconceptualizing (17) – Rethinking or redefining a concept.
  54. Overintellectualized (20) – Having been analyzed too much or in a too-intellectual way.
  55. Misunderstandingly (18) – In a manner of misunderstanding something.
  56. Uncharacteristically (20) – In a way that is unusual for someone or something.
  57. Disenfranchisements (19) – The acts of depriving someone of the right to vote.
  58. Overcommercialization (21) – The process of making something excessively commercial.
  59. Disenfranchisement (19) – The state of being deprived of the right to vote.
  60. Transubstantiation (18) – The belief in the transformation of substances, often used in religious contexts.
  61. Irreconcilabilities (19) – The state of being impossible to reconcile.
  62. Counterproductively (19) – In a way that is counter to achieving a goal.
  63. Disproportionately (18) – In a way that is out of proportion.
  64. Incomprehensibility (19) – The quality of being impossible to understand.
  65. Individualization (17) – The process of making something suited to an individual.
  66. Counterrevolutionary (20) – Opposed to a revolution.
  67. Underrepresentation (19) – The state of being inadequately represented.
  68. Hypersensitiveness (18) – Excessive sensitivity to stimuli.
  69. Intercontinentalism (19) – Involving two or more continents.
  70. Antidiscriminatory (18) – Opposed to discrimination.
  71. Misinterpretation (18) – A wrong or incorrect understanding.
  72. Overindustrialization (21) – Excessive industrial development.
  73. Hyperresponsiveness (19) – Excessive reaction to stimuli.
  74. Individualistically (18) – In a way that emphasizes personal independence.
  75. Antiauthoritarianism (20) – Opposed to authority or authoritarian systems.
  76. Unquestionableness (18) – The quality of being beyond question.
  77. Extraterrestriality (19) – The existence or origin of life beyond Earth.
  78. Noninterchangeable (18) – Not able to be exchanged.
  79. Institutionalizing (18) – The act of establishing something as a formal institution.
  80. Overproliferation (17) – The excessive increase of something.
  81. Thermodynamically (17) – In relation to the science of heat and energy.
  82. Transcendentalism (17) – The philosophy that emphasizes spiritual over material reality.
  83. Electrocardiograms (18) – Records of the electrical activity of the heart.
  84. Electrocardiograph (18) – An instrument for recording the electrical activity of the heart.
  85. Overcomplications (17) – The state of being unnecessarily complicated.
  86. Hyperconsciousness (18) – An extreme awareness of one’s own thoughts or actions.
  87. Ununderstandability (19) – The quality of being impossible to understand.
  88. Underappreciation (17) – The state of not being sufficiently appreciated.
  89. Electrotherapies (16) – Medical treatments that use electricity.
  90. Counterrevolutions (18) – Movements or actions that oppose a revolution.

Check out this interesting video about the world’s longest long words:

YouTube Video by RobWords — Long Words

How to Use Long Words

So you’ve learned some colossal words—now what? Here are a few ways you can actually use these gigantic words to your advantage (and sound like a genius in the process).

For Language Learners

Learning long words can be an excellent way to boost your English vocabulary, especially if you’re a non-native speaker aiming to master complex expressions.

Start by breaking down these words into smaller parts, or morphemes, to understand their root meanings.

For example, in the word “antidisestablishmentarianism,” each segment can tell you something about the word’s meaning.

Practicing with long words can also help with pronunciation skills and improve your confidence when using English in formal settings.

Plus, it’s a great way to show off in advanced language classes.

For Trivia Champions

Let’s face it—nothing impresses your trivia team quite like dropping a 30-letter word in the middle of a tough quiz.

Long words like “floccinaucinihilipilification” or “pneumonoultramicroscopicsilicovolcanoconiosis” are crowd-pleasers in the world of trivia. Memorizing these words (and knowing their definitions) will make you the star of trivia night, especially when a question about obscure vocabulary or medical terminology comes up.

Plus, if the category involves spelling, your knowledge could give you that winning edge.

For Teachers

If you’re a teacher, long words can be a fantastic educational tool.

They’re perfect for vocabulary building, showing students how English can be playful, challenging, and even a little ridiculous.

You can use long words to introduce students to etymology—teaching them how smaller root words and prefixes combine to form larger ones.

And let’s be honest, students will always get a kick out of trying to pronounce “hippopotomonstrosesquipedaliophobia.”

You can also use these long words to spice up spelling bees, making them more challenging and engaging for students of all levels.

Feel free to try out these colossal words the next time you want to impress, educate, or entertain!

Final Thoughts: Long Words in English

Once you get bitten by the word nerd bug, there is no saving you.

Keep binge-learning more words with the treasure-trove of guides listed below. You know you want to. I suggest you start with the very first one and work your way down through the rest.

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