What Is the Longest Word in English? Hint: It’s 189,819 Letters Long

Move over, "antidisestablishmentarianism." The longest word in English will leave you speechless.


“I know the longest word in the whole English language,” Jimmy tells Jenny by the playground swings. “It’s antidisestablishmentarianism.”

Jenny slurps up the last of her juice box, unimpressed. “Is that all?” she claps back. “Well I know an even longer word.” She sets down her juice, stands up straight, and takes a deep breath. “The longest word in English is Methionylalanylthreonylserylarginylglycylalanylseryl…”

“That’s not a real word!” Jimmy interrupts. Jenny continues.


“Come on. You’re making that up.”


“Jenny stop.”





But Jenny does not stop speaking for three and a half hours—long after Jimmy flees the playground in tears. As she utters the final syllables (“…leucine”), Jenny completes the full, technical name of the protein better known as titin—a folded, spring-like protein that helps keep our muscles elastic. Total letter count: 189,819.  English isn’t always easy—especially when you throw in regional sayings.

What does the longest word in English mean?

If you, like Jimmy, don’t think this monstrous moniker should be considered a real English word, you’d find some support from linguists. As a technical scientific term, the full name of titin doesn’t appear in any dictionary—not just because it would take 12 full pages to wrangle the 190,000-odd characters, but because of the way protein names are generated. According to international guidelines, a protein’s technical title lists every single amino acid found inside it. Even the smallest proteins contain no fewer than 20 amino acids, making for some pretty long names in their own right; titin, however, is the human body’s largest protein. Total amino acid count: 34,350. Spell out each of those acid names in a row and you get, well, a really long word. (You can see why scientists prefer titin.)  If you thought the longest word in English was hard to pronounce, start off with these English words that are hard to pronounce but aren’t nearly as long.

So, if dictionary editors don’t dare to spare their pages on titin’s full name, what is the longest word in the dictionary? That depends on which dictionary you consult. A few contenders:

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  • The longest word in the Oxford English Dictionary is 45 letters longPneumonoultramicroscopicsilicovolcanoconiosis. According to the OED, this synonym for silicosis was coined in the 1930s as a jab at overly-complicated medical terms. Yep, the longest word in the dictionary is a joke.
  • The longest well-known nonsense word is 34 lettersSupercalifragilisticexpialidocious. Anyone versed in their Mary Poppins can define this for themselves, but according to Oxford the fanciful adjective means “extraordinarily good.”
  • The longest non-coined, non-technical word published in multiple dictionaries is 28 letters longAntidisestablishmentarianism. (Yep, Jimmy was right about that one—even if Merriam-Webster refuses to include it in their pages due to a lack of long-term use). What does it actually mean? It used to refer a 19th-century political party opposed to the disestablishment of the Church of England—but today it mainly means “I know a really long word.”

Fun fact: The North Island of New Zealand holds the world record for the longest town name with 85 letters: Taumatawhakatangihangakoauauotamateaturipukakapikimaungahoronukupokaiwhenuakitanatahu. Locals call it Taumata or Taumata Hill.

It’ll take you too long to say these words at the dinner table, but uttering other fancy words will make you sound smarter in a shorter amount of time.

Debate rages between word nerds as to which of these is the true “longest word in English.”  When it comes to our constantly-evolving language, your opinion is as valid as anyone’s. So, if this is the sort of distinction you care about, we’ve got some more brain food for you: With 645 meanings, the most complicated word in English is only three letters long.