Nexus

n. means of connection, link, joint; connected group

Plural; "Nexi". A nexus is a connection or the centre of something.
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Nexus /nex·us/ pl. nex´us [L.] 1. a bond, especially one between members of a series or group. 2. gap junction. nex·us n. pl. [more]Nexus - Community and Resources

Noun
1. the means of connection between things linked in series
(synonym) link
(hypernym) linkage
2. a connected series or group
(hypernym) series

(n.)
Connection; tie.