When nexus came into English in the 17th century, it meant “connection” or “link.” Eventually, people began using it to refer to a connected group or series of things, as in “a nexus of relationships.”

n. pl. nexus or nex·us·es 1. A means of connection; a link or tie: "this nexus between New York's... real-estate investors and its... politicians" (Wall Street Journal). 2. A connected series or group. 3. The core or center: "The real nexus of the money culture [was] Wall Street" (Bill Barol).

nexus [ nek -s uh s ] Phonetic (Standard)IPA noun, plural nex·us·es, nex·us. a means of connection; tie; link. a connected series or group. the core or center, as of a matter or situation.