Der or DER may refer to:
Places Darkənd, Azerbaijan Dearborn (Amtrak station) (station code), in Michigan, US Der (Sumer), an ancient city located in modern-day Iraq d'Entrecasteaux Ridge, an oceanic ridge in the south-west Pacific Ocean
Science and technology Derivative chromosome, a structurally rearranged chromosome Distinguished Encoding Rules, a method for encoding a data object, including public key infrastructure certificates and keys Distributed Energy Resources ∂, the partial derivative symbol Derivation (differential algebra) on an algebra A over a field K, the space (module) of which is denoted DerK(A) Deep energy retrofit, an energy conservation measure
Organizations Digital Education Revolution, former Australian Government-funded educational reform program DER rental (Domestic Electric Rentals Ltd), a UK television rentals company Documentary Educational Resources, a non-profit film producer and distributor
Other uses Defence (Emergency) Regulations, legal regulations promulgated by the British in Mandatory Palestine in 1945 Department of Environment Regulation, former Western Australian state government department Designated Engineering Representative, an individual appointed to approve, or recommend approval, of technical data to the Federal Aviation Administration d3r, (Real name Andreas Tarasoff) a 21-year old singer from British Columbia, Canada