The longest word in any of the major English language dictionaries is pneumonoultramicroscopicsilicovolcanoconiosis

yes,   the longest English word is -“pneumonoultramicroscopicsilicovolcanoconiosis”

Which means, according to the Google dictionary,  an invented long word said to mean a lung disease caused by inhaling very fine ash and sand dust.

This word invented  probably by Everett M. Smith, president of the National Puzzlers’ League in 1930s.

This word “pneumonoultramicroscopicsilicovolcanoconiosis” used in  in imitation of very long medical terms.

Thanks for the questions.