The longest word in the major English dictionaries is pneumonoultramicroscopicsilicovolcanoconiosis, which consists of 45 letters and is supposed to mean a lung disease silicosis. Of these, pneumo- means "lung", ultra- "ultra", micro- "micro", microscopic "microscopic", silico- "silicon", volcano "volcano", coni- "dust", -osis "dust", and -osis "dust". ", and -osis as a suffix for disease. Researchers later concluded it was a hoax.

In the Guinness Book of World Records, published in 1992, it was argued that the "truly longest single word" would be the 29-letter word floccinaucinihilipilification, meaning "to estimate or rate something as worthless/disdainful". value/disdain". This usage is recorded as having been used in 1741. More recently, it was recorded in the minutes of the U.S. Senate, by Rob Beyer [1], and in the White House by Bill Clinton's press secretary, Mike McCurry, although, ironically, it is the longest single word in the first edition of the Oxford Dictionary for a non-technical proper noun.

Antidisestablishmentarianism (the nineteenth-century British movement against the separation of church and state) is also one of the long single words.

The longest word in Shakespeare's works is honorificabilitudinitatibus in Love's Labour's Lost, a controversial word in English (and in Latin, too), but he used it anyway.

humuhumu-nukunuku-a-pua'a, or cited goldfish, is the state fish of Hawaii[1] and consists of 21 letters. It is also the only long monogram of a well-known animal name. The word is often said to be longer than a fish.

Although only fourteen letters long, sesquipedalian (polysyllabic) is also a noteworthy word. It is derived from the "nonce word" (a special word used only in specific areas) used in the work of a Roman writer, Horace: Ars Poetica. The original is as follows: "Proicit ampullas et sesquipedalia verba," which means, "He throws aside his paint pots and his words that are a foot and a half long".