The Longest Word in the English Language

It’s 189,819 letters long

methionyl​threonyl​threonyl​glutaminyl​alanyl​prolyl​threonyl​phenyl​alanyl​threonyl​glutaminyl​prolyl​leucyl​glutaminyl​seryl​valyl​valyl​valyl​leucyl​glutamyl​glycyl​seryl​threonyl​alanyl​threonyl​phenyl​alanyl​glutamyl​alanyl​histidyl​isoleucyl​seryl​glycyl​phenyl​alanyl​prolyl​valyl​prolyl​glutamyl​valyl​seryl​tryptophyl​phenyl​alanyl​arginyl​aspar