district of London, so called because it was laid out c. 1768 and built by four brothers of a family named Adam; from Greek adelphos "brother," literally "from the same womb, co-uterine," from copulative prefix a- "together with" (see a- (3)) + delphys "womb," which is perhaps related to dolphin. The district was the site of the popular Adelphi theater c. 1882-1900, which gave its name to a style of performance.