These Are the LONGEST English Words in the Dictionary
March 24, 2025
Want to impress your friends with some ridiculously and perhaps unnecessarily long words? This is the list for you!
The 190,000-Letter Word
Number of Letters: 189,819
Definition: Yep, there’s a word out there that’s almost 190,000 letters long. Technically speaking, it’s not truly a word—it’s actually the chemical name for a protein. Luckily, this protein has a much shorter nickname: titin! This is the largest protein chain in the human body, which makes its super-long chemical name quite appropriate. The name starts with “methionylthreonylthreonylglutaminyl . . . ” and continues for a WHILE. In fact, it takes over three hours to say it all.
The Longest Place Name: Lake Chargoggagoggmanchauggauggagoggchaubunagungamaugg
Number of Letters: 49 (or 53, if you count “Lake”)
Definition: Lake Chargoggagoggmanchauggauggagoggchaubunagungamaugg is in Webster, Massachusetts. Locals usually just refer to it as “Webster Lake,” though, and who can blame them?
Pneumonoultramicroscopicsilicovolcanoconiosis
Number of Letters: 45
Definition: a lung disease (pneumoconiosis) that is caused by inhalation of very fine silicate or quartz dust
Supercalifragilisticexpialidocious
Number of Letters: 34
Definition: Per Mary Poppins, this whimsical word is the perfect thing to say when you have nothing else to say.
Pseudopseudohypoparathyroidism
Number of Letters: 30
Definition: a rare, usually inherited, endocrine disorder that clinically resembles pseudohypoparathyroidism but in which calcium and phosphate blood levels are normal and there is no impaired ability of the body to respond to parathyroid hormone; This disorder causes short stature, round face, and short hand bones.
Floccinaucinihilipilification
Number of Letters: 29
Definition: the act of estimating something as worthless (e.g., “I loved him for nothing so much as his floccinaucinihilipilification of money.”)
Methylenedioxymethamphetamine
Number of Letters: 29
Definition: This drug has a nickname that might be more familiar: ecstasy. This is a synthetic amphetamine that is used illegally for its hallucinogenic properties.
Antidisestablishmentarianism
Number of Letters: 28
Definition: opposition to the disestablishment of the Church of England; more generally, it could be used to mean opposition to the breaking away from any established religious organization.
Electroencephalographically
Number of Letters: 27
Definition: An electroencephalograph is an apparatus for detecting and recording brain waves; therefore, doing something electroencephalographically means you do it using that machine.
Radioimmunoelectrophoresis
Number of Letters: 26
Definition: immunoelectrophoresis in which the substances separated in the electrophoretic system are identified by radioactive labels on antigens or antibodies (Just in case you—like me—have no idea what “immunoelectrophoresis is, that’s an “electrophoretic separation of proteins followed by identification by the formation of precipitates through specific immunologic reactions.” Glad we cleared that up.)
Immunoelectrophoretically
Number of Letters: 25
Definition: As noted in the above entry, immunoelectrophoresis is the electrophoretic separation of proteins followed by identification by the formation of precipitates through specific immunologic reactions. Therefore, if you do something immunoelectrophoretically, you do it by using immunoelectrophoresis.
Laryngotracheobronchitis
Number of Letters: 24
Definition: inflammation of the larynx, trachea, and bronchi; this condition is marked by tissue swelling and the excessive secretion of mucus, which generally leads to the obstruction of respiratory passages.
Hydrochlorofluorocarbon
Number of Letters: 23
Definition: any of several simple gaseous compounds that contain carbon, chlorine, fluorine, and hydrogen (also known as HCFC)
Most of the words we’ve listed so far are medical or scientific terms. However, there are some pretty darn long words that are more common, too! Here are a few examples:
Counterrevolutionaries
Number of Letters: 22
Definition: people who participate in a revolution directed toward overthrowing a government or social system established by a previous revolution (So if a country experiences a revolution and that revolution is successful but then another revolution comes along to overthrow that first revolution, the second revolution is the counterrevolutionaries.)
Deinstitutionalization
Number of Letters: 22
Definition: the release of institutionalized individuals from institutional care (as in a psychiatric hospital) to care in the community; the reform or modification of an institution to remove or disguise its institutional character
Finally, we have to end with the most fitting entry of all:
Sesquipedalianism
Number of Letters: 17
Definition: sesquipedalian means “having many syllables” or “given to or characterized by the use of long words.” Therefore, sesquipedalianism is the practice of using very long words.
Which word on this list is your favorite? And what other super-long words can you think of? Let me know in the comments!
Click here to check out the 10 most-searched words in the dictionary!
Source:
- “America’s Most Trusted Dictionary.” Merriam-Webster. Accessed August 7, 2024. https://www.merriam-webster.com/.
- “Home : Oxford English Dictionary.” OED. Accessed March 24, 2025. https://www.oed.com/.