Chemical name of Dahlemense Strain of Tobacco Mosaic Virus is 3rd longest in English language, apparently (not sure I'd want to have a conversation with anyone who thinks this is really a valid English word, but anyway):
acetylseryltyrosylserylisoleucylthreonylserylproly lserylglutaminyl-
phenylalanylvalylphenylalanylleucylserylserylvalyl tryptophylalanyl-
aspartylprolylisoleucylglutamylleucylleucylasparag inylvalylcysteinyl-
threonylserylserylleucylglycylasparaginylglutaminy lphenylalanyl-
glutaminylthreonylglutaminylglutaminylalanylarginy lthreonylthreonyl-
glutaminylvalylglutaminylglutaminylphenylalanylser ylglutaminylvalyl-
tryptophyllysylprolylphenylalanylprolylglutaminyls erylthreonylvalyl-
arginylphenylalanylprolylglycylaspartylvalyltyrosy llysylvalyltyrosyl-
arginyltyrosylasparaginylalanylvalylleucylaspartyl prolylleucylisoleucyl-
threonylalanylleucylleucylglycylthreonylphenylalan ylaspartylthreonyl-
arginylasparaginylarginylisoleucylisoleucylglutamy lvalylglutamyl-
asparaginylglutaminylglutaminylserylprolylthreonyl threonylalanylglutamyl-
threonylleucylaspartylalanylthreonylarginylarginyl valylaspartylaspartyl-
alanylthreonylvalylalanylisoleucylarginylserylalan ylasparaginylisoleucyl-
asparaginylleucylvalylasparaginylglutamylleucylval ylarginylglycyl-
threonylglycylleucyltyrosylasparaginylglutaminylas paraginylthreonyl-
phenylalanylglutamylserylmethionylserylglycylleucy lvalyltryptophyl-
threonylserylalanylprolylalanylserine
