10 Longest Words in the English Language

Last Updated: Dec 30, 2019
How many words exactly are in the English language? The second edition of the current 20-volume Oxford English Dictionary contains 171,476 words in current use. That’s a lot! Which gets the mind thinking the next question, what’s the longest word in current use today?

Many of the longest words in the dictionary refer to medicine or chemistry. You’ll find a few defined in here along with other long words that you may or may not already use. Here’s how Merriam-Webster defines the ten longest words in the English language.

1. Pneumonoultramicroscopicsilicovolcanoconiosis (45 letters)

Pneumoconiosis caused by inhalation of very fine silicate or quartz dust.

2. Hippopotomonstrosesquippedaliophobia (36 letters)

Ironically, Hippopotomonstrosesquippedaliophobia is one of the longest work in the dictionary and is the name for a fear of long words! Who would have thought, right?

3. Supercalifragilisticexpialidocious (34 letters)

Perhaps the best word of all! Made popular by the film Mary Poppins, Supercalifragilisticexpialidocious is something to say when you have nothing to say.

4. Pseudopseudohypoparathyroidism (30 letters)

A relatively mild form of pseudohypoparathyroidism that is characterized by normal levels of calcium and phosphorus in the blood.

5. Floccinaucinihilipilification (29 letters)

The longest unchallenged nontechnical word that not all directories recognize, that including Merriam-Webster. According to alternative sources, floccinaucinihilipilification is the act or habit of describing or regarding something as unimportant, of having no value or being worthless. Often times, it is used in a humorous way.

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6. Antidisestablishmentarianism (28 letters)

A term referring to a political movement in 19th century Britain that sought to separate church and state. In this case, political movement wanted to disestablish the Church of England as the official state church of England, Ireland and Wales.

7. Honorificabilitudinitatibus (27 letters)

The longest word in Shakespeare’s works. Honorificabilitudinitatibus is the longest word in the English language featuring alternating consonants and vowels.

8. Thyroparathyroidectomized (25 letters)

A medical term that defines the excision of both the thyroid and parathyroid glands.

9. Dichlorodifluoromethane (23 letters)

A chlorofluoromethane CF2Cl2.

10. Incomprehensibilities (21 letters)

Impossible to comprehend. In the 1990’s, incomprehensibilities set the record as the longest word “in common usage.”

LONGEST ENGLISH WORD:Methionylthreonylthreonylglutaminylarginyl…isoleucine (189,819 letters)

If we’re talking chemistry, the longest chemical name is 189,819 letters long. It is the chemical name for titin, a giant filamentous protein essential to the structure, development, and elasticity of muscle. As to whether or not this is an actual word is disputed by many. It is not in the Merriam-Webster dictionary, so you shouldn’t ever have to worry about spelling it. ?