The longest word in our dictionary is chromophotolithograph, at 21 letters. Three words tie for second place at 20 letters: contradistinguishing, crystallographically and philoprogenitiveness. These are the longest single entries in the 1913 Webster’s Unabridged Dictionary, the source of MyWordSolver’s 106,000-word database, which is why famous giants like antidisestablishmentarianism don’t appear.
To build this list, we ranked every entry in our database by length and removed one data artifact, a run-together fragment that isn’t a real word. The 24 words below are genuine entries. Most are scientific or technical, which is typical of the longest words in any large dictionary.
The 10 longest words and what they mean
Several words share the same length, so ranks 5 to 10 are all 19-letter ties, listed in the order they appear in our length ranking.
| Rank | Word | Letters | What it means |
|---|---|---|---|
| 1 | chromophotolithograph | 21 | A color print made by lithography, using images put onto the printing surface by photography. |
| 2 | contradistinguishing | 20 | Telling things apart by pointing out how they contrast. |
| 3 | crystallographically | 20 | In terms of crystallography, the science of the structure and shape of crystals. |
| 4 | philoprogenitiveness | 20 | Love of one’s own children; also, a tendency to have many offspring. Phrenologists counted it as one of the mind’s “faculties”. |
| 5 | hydrometeorological | 19 | Relating to water in the atmosphere, such as rain, snow, hail and fog, or to the study of it. |
| 6 | incomprehensibility | 19 | The quality of being impossible to understand. |
| 7 | hypocraterimorphous | 19 | In botany, salver-shaped: describing a flower with a long, narrow tube that opens out flat, as in phlox. |
| 8 | conventionalization | 19 | The act of making something conventional; in art, showing a natural form in a simplified, stylized way. |
| 9 | extraterritoriality | 19 | Freedom from local law, such as the immunity ambassadors enjoy in a foreign country. |
| 10 | interstratification | 19 | In geology, the state of lying between other layers of rock, or of alternating with them. |
The rest of the top 24
More 19-letter words
- historiographership: the office of a historiographer, an officially appointed historian.
- cartilaginification: the process of turning into cartilage.
- distinguishableness: the quality of being distinguishable.
- contradistinguished: the past tense of contradistinguish.
- incontrovertibility: the quality of being impossible to dispute.
18-letter words
These nine fill the remaining places in our top 25 by length (the one other place in the top 25 belonged to the artifact we removed).
- crystallographical: relating to crystallography.
- tetrakishexahedron: a solid with 24 triangular faces, like a cube with a low pyramid built on each face.
- insurmountableness: the quality of being impossible to overcome.
- branchiogastropoda: an old zoological name for snails and other gastropods that breathe through gills.
- parallelogrammical: shaped like a parallelogram.
- hypermetamorphosis: an insect life cycle with extra larval stages, as seen in blister beetles.
- characteristically: in a way that is typical of someone or something.
- intercartilaginous: located between cartilages.
- chromolithographic: relating to chromolithography, color printing from stone or metal plates.
How the longest words are built
Nobody invents a 20-letter word from scratch. Almost every word on this list is a short root with prefixes and suffixes stacked onto it. Take distinguish (11 letters): add -able and you get distinguishable (15), add -ness and you reach distinguishableness (19). Put contra- on the front instead and you get contradistinguishing (20).
Looking across all 24 words, a few building blocks do most of the work:
| Building block | Words on the list | Examples |
|---|---|---|
| -ical or -ically ending | 5 | hydrometeorological, crystallographically, characteristically |
| -ness ending | 3 | philoprogenitiveness, distinguishableness, insurmountableness |
| -ity ending | 3 | incomprehensibility, extraterritoriality, incontrovertibility |
| -ation ending | 3 | conventionalization, interstratification, cartilaginification |
| -ous ending | 2 | hypocraterimorphous, intercartilaginous |
| the root “graph” | 5 | chromophotolithograph, historiographership, chromolithographic |
| the root “distinguish” | 3 | contradistinguishing, contradistinguished, distinguishableness |
A few more patterns from the data:
- The average length is 18.8 letters, across 452 letters in total.
- Nine of the 24 start with C, thanks to roots like chromo-, crystallo-, contra- and cartilag-.
- I is the most used letter, appearing 56 times, ahead of R (42) and O (41). That reverses the pattern in 5-letter words, where E is the most common letter: here E appears only 27 times. Suffixes such as -ity, -ification and -ically are full of I’s.
- Eight of the 24 contain a double letter. Crystallographically has two LL’s, and parallelogrammical has both LL and MM. For more on doubles, see our guide to words with double letters.
Taking apart chromophotolithograph
The winner is really four Greek roots in a row:
- chromo-: color
- photo-: light
- litho-: stone
- -graph: something drawn or written
Put together, it describes a 19th-century printing process. Lithography prints from a flat stone or plate; chromolithography uses a separate stone for each color; and the “photo” part means the image was put onto the stones photographically rather than drawn by hand.
Why the famous long words aren’t here
Since nothing in our database runs longer than 21 letters, none of the well-known record holders is a single entry in it:
- antidisestablishmentarianism (28 letters): opposition to removing the Church of England’s status as the official state church.
- floccinaucinihilipilification (29 letters): the act of judging something to be worthless.
- supercalifragilisticexpialidocious (34 letters): made famous by the 1964 film Mary Poppins.
- pneumonoultramicroscopicsilicovolcanoconiosis (45 letters): a lung disease name coined in the 1930s, largely to be long.
The last two came along after 1913 in any case. The first two are older, but a dictionary records the words people actually write, and record-breakers are better known as trivia than as working vocabulary.
Long words in word games
Scrabble
A standard Scrabble board is 15 squares wide, so the longest word you can ever play is 15 letters. Every word on this page is too long. If you want to look for the longest playable words, start with our lists of 15 letter words starting with double letters and 14 letter words ending with double letters.
Long names
Some of the longest strings of letters you’ll meet in puzzles are names rather than dictionary words. Dinosaur names often run longer than anything in the 1913 Webster’s: see our 19 letter dinosaur names and 20 letter dinosaur names. Bird watchers have their own record-setters, collected in our list of long bird names.
At the other extreme
If long words are one kind of word-lover’s trophy, palindromes are another. Our list of every palindrome in the dictionary tops out at nine letters, with a word that reads the same in both directions.