Some special words in English

Some of the extra long words in the English language:
Pneumonoultramicroscopicsilicovolcanoconiosis
This 45-letter word is the longest word in the English dictionary and refers to a lung disease caused by inhaling silica dust. It's a combination of Latin terms and is also known as "P45" by researchers.
Pseudopseudohypoparathyroidism
This 30-letter word refers to an inherited disorder.
Floccinaucinihilipilification
This 29-letter word means the act of estimating something as being worth so little as to be practically valueless.
Antidisestablishmentarianism
This 28-letter word refers to a 19th-century political movement that opposed the disestablishment of the Church of England as the state church of England. 
The English language allows for the creation of arbitrarily long words by adding prefixes and suffixes to existing words. This process is called agglutinative construction.
 Supercalifragilisticexpialidocious (thirty-four letters)
Mary Poppins described it as the word to use “when you have nothing to say.” It appears in some (but not all) dictionaries.
 Incomprehensibilities (twenty-one-letters)
This word set the record in the 1990s as the longest word “in common usage.”
Uncopyrightable and subdermatoglyphic
Isograms are words that do not repeat letters. The longest examples are uncopyrightable and subdermatoglyphic.
An uncopyrightable song, for example, would not be eligible for copyright. This word has fifteen letters, but one other word without repeated letters is longer—subdermatoglyphic. It’s seventeen letters, but you’ll not have much opportunity to use it outside the realm of dermatology.
Sesquipedalianism
The fourteenth word on our list describes the tendency to use long words—sesquipedalianism
Strengths
Strengths has only nine letters, but all except one of them are consonants! This earns the word a Guinness World Record. It is also one of the longest monosyllabic words of the English language.
Euouae
Euouae is six letters long, but all of the letters are vowels. It holds two Guinness World Records. It’s the longest English word composed exclusively of vowels, and it has the most consecutive vowels of any word. If you are wondering about its meaning, it’s a musical term from medieval times.
Unimaginatively
Unimaginatively has lots of vowels—eight in total, if you count the final y. What’s neat about this word is that its vowels and consonants alternate. It’s not the longest word with alternating consonants and vowels, though.
Honorificabilitudinitatibus
That position is held by honorificabilitudinitatibus, a twenty-seven-letter way of saying “with honorableness.”
 Tsktsk
If you tsktsk someone, you indicate your disapproval by the tsktsk sound or by some other means. Tsktsks is the longest word that doesn’t contain a vowel.