The longest word in the English language is pneumonoultramicroscopicsilicovolcanokoniosis, with 45 letters. It is an obscure term for a lung disease. The next longest word is the medical term hepaticocholangiocholecystenterostomies, which has 37 letters.
The longest word is debatable, according to fun-with-words.com, because some words, such as pneumonoultramicroscopicsilicovolcanoconiosis and antidisestablishmentarianism, which many children learn in school, are made up or only defined as long words.
Some chemical names describing a molecule's structure are so long they are never used. One chemical name has 1,185 letters. Two chemical terms, with 3,641 letters and 1,913 letters, were entered and then withdrawn from the Guinness Book of World Records, because they've never been used by chemists.
The longest non-English word is a compound Sanskrit word, describing a region of India, according to Guinness World Records. It is a compound word of 195 Sanskrit characters, or 428 English letters.
The longest place name in the world is Taumatawhakatangihangakoauauotamateaturipukakapikimaungahoronukupokaiwhenuakitanatahu, with 85 letters. It's a Maori word for a hill in New Zealand that is usually shortened to Taumata. Another long place name is Gorsafawddachaidraigodanheddogleddolonpenrhynareurdraethceredigion, a town in Wales, with 66 letters.
The Guinness World Record for the longest palindrome, a word that is spelled the same way forward and backward, is saippuakivikauppias, with 19 letters. It’s Finnish for someone who sells lye.