13 Words with more than 20 letters

1. UNDERCHARACTERIZATION
2. buckminsterfullerenes
3. electroencephalograph
4. Supercalifragilisticexpialidocious
5. incomprehensibilities
6. ANTIDISESTABLISHMENTARIANISM
7. Floccinaucinihilipilification
8. Hexakosioihexekontahexaphobia - Fear of the number 666
9. ANTITRANSUBSTANTIATIONALIST
10. phosphatidylethanolamine
11. Disproportionableness
12. radioimmunoelectrophoresis
13. DIPHENYLAMINECHLOROARSINE