None of these are right... I'm my dictionary it says it and this is the meaning of the word " this word contains 1909 letters. It is the term for the formula C1289H2051N3430375S8. A tryptophan synthetase A protein, an enzyme that has 267 amino acids."
As the largest known protein, titin also has the longest IUPAC name. The full chemical name, which starts methionyl... and ends ...isoleucine, contains 189,819 letters and is sometimes stated to be the longest word in the English language, or any language. It can take over three hours to pronounce.
The longest word that is actually a word is pneumonoultramicroscopicsilicovolcaniconiosis. It's is the medical term for a disease called silicosis, cause by breathing in very fine silica or quartz dust. Like one of the answers above said, there is a term for a chemical process with 1909 letters, but a chemical process is not actually a word.