capelli

Capelli is an Italian noun meaning hair, specifically the hair on a person’s head. It is almost always used in the plural form i capelli, as Italian treats hair collectively as a plural noun. Phrases describe color, length, and texture, for example: capelli lunghi (long hair), capelli neri (black hair), capelli grigi (gray hair). The singular form capello exists in Italian, but it is primarily used for the word hat ( cappello ); in modern usage the singular for hair is not commonly employed.

The term derives from Latin capillus and has long been part of Italian vocabulary for everyday speech, fashion, and literature. Capelli is also a surname of Italian origin; individuals bearing the name have appeared in various professions.

In mathematics, Capelli's identity is a classical theorem in invariant theory named after the Italian mathematician Giuseppe Capelli. It relates determinants involving differential operators and has served as a tool in the development of noncommutative algebra and invariant theory.

In other contexts, Capelli appears in idiomatic expressions such as capelli d’angelo (angel hair) in culinary or poetic usage, and in references to hair texture, such as capelli lisci (straight hair). The term also appears in cultural and historical contexts where Italian language and heritage intersect with art, fashion, and science.