JetBlue is a Limited Will Carry carrier as outlined by OPSPEC - A055.
Hazardous materials include, without limitation, any type of explosives, corrosives, poisons, flammable gases, liquids or solids, nonflammable compressed gases, radioactive materials, magnetized materials and oxidizing agents.
For the most complete list of hazardous materials and what can and cannot be brought on an airplane, visit the FAA's website here. The following items are examples of hazardous materials or dangerous goods and are not allowed as carry-on items or in checked bags: