The longest word in English that appears in at least some dictionaries is “pneumonoultramicroscopicsilicovolcanoconiosis,” which has 45 letters. It is the name of a lung disease (pneumono) that is caused by inhaling very small (ultramicroscopic) silicone particles from a volcano. The term was coined specifically to serve as an example of a long word.
The second-longest word is “pseudopseudohypoparathyroidism” (30 letters), which is a rare genetic disorder that mimics the symptoms of a thyroid disorder.
Very long words are able to be created in English by adding prefixes and suffixes on to a base word. This process is essentially limitless, which is why most long words have several prefixes and suffixes.
Want to add more long words to your writing? Try out QuillBot’s free Paraphrasing Tool.