The word that has 42 letters is parastratiosphecomyiastratiosphecomyioides.
The word parastratiosphecomyiastratiosphecomyioides is the longest accepted binomial construction with 42 letters.
And parastratiosphecomyiastratiosphecomyioides refers to a species of fly that is native to Thailand and is also one of the words that has made it to the dictionary.
The Parastratiosphecomyia, also known by its also long common name Southeast Asian soldier fly, was discovered in 1923 by British entomologist Enrico Brunetti.
Another word that is long is Taumatawhakatangihangakoauauotamateaturipukakapikimaungahoronukupokaiwhenuakitanatahu.
This 1,000-foot hill near the township Porangahau holds the Guinness World Record for longest place name with 85 characters. Locals call it Taumata or Taumata Hill.