Any fruit of a plant of the botanical genus Capsicum, which has a spicy/burning flavour because it contains capsaicin. (Not all chili peppers are particularly spicy, but all true chili peppers contain some capsaicin, in contrast to e.g. the bell pepper, which is not a true chili pepper and does not.)
Any of various small peppers of highly notable pungency or heat.
Any of the plants that bear such fruit, especially the species Capsicum annuum and Capsicum frutescens and their numerous subspecies, varieties, or cultivars.