Chillies are fruits.
Botanically speaking, a fruit is the mature ovary of a flowering plant, containing seeds. Chillies, derived from the Capsicum plant, fit this definition perfectly. They develop from the flower and contain seeds within their fleshy walls.
While we often use the term "vegetable" in everyday language, it's not a scientific classification. Vegetables are typically defined as the edible parts of plants that are not fruits, such as roots, stems, leaves, and bulbs.
Therefore, despite being used in savory dishes and often categorized as vegetables in our culinary world, chillies are scientifically classified as fruits due to their origin and structure.