Mammoth Uncensored Word List:
18 - 21 letter words starting with c

chemolithoheterotroph chemolithotrophically cholecystogastrostomy cholecystojejunostomy cholecystolithotripsy cholecystonephrostomy chronostratigraphists clinicopathologically colpoperineorrhaphies compartmentalisations compartmentalizations constitutionalization contemporaneousnesses countercountermeasure counterdemonstrations counterinterpretation counterproductiveness crystalloluminescence