1. Pneumonoultramicroscopicsilicovolcanoconiosis (45 letters)A supposed lung disease 2. Hippopotomonstrosesquippedaliophobia (36 letters)Fear of long words.3. Supercalifragilisticexpialidocious (34 letters)It is something to say when you have nothing to say.4. Pseudopseudohypoparathyroidism (30 letters)It is characterized by normal levels of calcium and phosphorus in the blood.5. Floccinaucinihilipilification (29 letters)It is the act or habit of describing or regarding something as unimportant, of having no value or being worthless. Many times, it is used in a humorous way.6. Antidisestablishmentarianism (28 letters)Opposed or hostile to the social, economic, and political principles of a ruling class (as of a nation). Opposed to the establishment.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. What about your language? What are the longest words?