A species of capsicum or hot peppers (chile, chili, or chilli).
The habanero and the scotch bonnet, both claimed to be the hottest variety of pepper are varieties of this same species.
The full taxonomy of Capsicum chinense is:
Heat as measured in Scoville Heat Units can range from 40,000 SHU for Datil peppers, through 100,000 SHU for scotch bonnets, 80,000 to 200,000 SHU for Orange Habaneros, all the way up to 577,000 SHU for the Red Savina Habanero - the hottest pepper ever tested.
The Latin name is actually a misnomer meaning Chinese capsicum. This is erroneous since all capsicums originate in the New World. The species was named in 1776 by Nikolaus von Jacquin, a Dutch physician who was collecting seeds in the Caribbean on behalf of Emperor Francis I, and thought they came from China.