Which is the biggest word in English? This is a matter of debate. Moreover, it is not a fixed issue. New word discovery is going on. As a result, the biggest word depends on the human point of view. So it is difficult to say which word is bigger/biggest. Under this situation few big words are discussed below. 

Let’s make a list of big words 

1. sesquipedalianism : The word has 17 letters. The meaning of the word is the tendency to use bigger words. 

2. subdermatoglyphic :  This word has 16 letters. It is used only in dermatology. 

3. honorificabilitudinitatibus  : The word has 27 letters.  

4.  Incomprehensibilities:  This was introduced in 19th century. At that time this was the biggest word.  It has 21 letters. 

5.  Supercalifragilisticexpialidocious : This has 34 letters.  The word means a situation when you have nothing to say. Of course, it does not appear in all dictionaries. 

6.  Antidisestablishmentarianism : The word has 28 letters. It was originally meant to protest against the anti-church sentiment in England. Now, of course, opposition to withdrawing government support from the church or religion is understood. There is no antidisestablishmentarianism in the Merriam-Webster Collegiate Dictionary, because the editors did not find a broad, consistent use of the original meaning of the word.  

7. electroencephalographically : electroencephalographically: This word is included in Merriam-Webster Collegiate Dictionary and other dictionaries. It has 27 letters. 

8. Floccinaucinihilipilification– The word has 29 letters. It  is used to measure of the futility of something. Its use is recorded up to 1741.9.    

9. Pseudopseudohypoparathyroidism– The word has 30 letters. Originally It is used in medical science. The Oxford English Dictionary contains Pseudoepsiudohypoparthyroidism (30 characters). 

10.   Pneumonoultramicroscopicsilicovolcanoconiosis– This word has 45 characters. The word is by far the largest English word in the world. It actually refers to a lung disease. This problem occurs when silica or quartz powder is inhaled. The word was deliberately created as the longest word in English. The Oxford English Dictionary does not contain the word. 

11.  Internationalization—It has 20 letters. The term has been used by more than a million people. The word is abbreviated “i18n”, the embedded number represents the number of letters between the first and last. The longest English word.