Places
*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 Der''K''(A) * Deep energy retrofit, an energy conservation measureOrganizations
* 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 distributorOther 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 {{disambiguation, geo