The chili pepper (also chile, chile pepper, chilli pepper, or chilli) from Nahuatl ch�«lli is the fruit of plants from the genus Capsicum which are members of the nightshade family, Solanaceae. Chili peppers are widely used in many cuisines as a spice to add heat to dishes. The substances giving chili peppers their intensity when ingested or applied topically are capsaicin and related compounds known as capsaicinoids.