Del, or nabla, is an operator used in mathematics, in particular, in vector calculus, as a vector differential operator, usually represented by the nabla symbol ∇. When applied to a function defined on a one-dimensional domain, it denotes its standard derivative as defined in calculus. When applied to a field (a function defined on a multi-dimensional domain), del may denote the gradient (locally steepest slope) of a scalar field (or sometimes of a vector field, as in the Navier–Stokes equations), the divergence of a vector field, or the curl (rotation) of a vector field, depending on the way it is applied.

Del or DEL may refer to:

• Alire Raffeneau Delile
• Del, vector differential operator represented by the symbol ∇ (nabla)
• Del, one of several names for the partial derivative symbol, ∂
• Del Thompson (born 1958), American football player
• Del, Iran, a village in West Azerbaijan Province, Iran
• Del Boy, fictional lead character in the BBC comedy Only Fools and Horses
• Del tha Funkee Homosapien, American hip hop artist
• Del Vaughn, CBS News correspondent
• Delaware, a U.S. state
• Delaware languages of Native Americans in the Delaware area (ISO code del)
• Delphinus (constellation)
• Department for Employment and Learning, part of the Northern Ireland government
• Deutsche Eishockey Liga, the premier ice hockey league in Germany
• DNA Encoded Chemical Library, a technology for the synthesis and screening of collections of chemical compounds
• Indira Gandhi International Airport, Delhi, India (IATA code DEL)

Canton of Grisons or Graubünden in German (Swiss Standard German: ; German Standard German: ; ; ; ; see also other names) is the largest and easternmost canton of Switzerland. The canton shares borders with the cantons of Ticino, Uri, Glarus and St. Gallen and international borders with Italy, Austria and Liechtenstein. The name Graubünden translates as the "Grey Leagues," referring to the canton's origin in three local alliances, the League of God's House, the Grey League, and the League of Ten Jurisdictions. Graubünden is also home to three of Switzerland's ethnic groups and the subsequent languages of Swiss German, Italian and Romansh are all native to the state. It is the only officially trilingual canton and the only canton where the Romansh language has official status.