The Collaborative International Dictionary of English v.0.48:

Nexus \Nex"us\, n. [L.]
   Connection; tie.
   [1913 Webster]

         Man is doubtless one by some subtile nexus . . .
         extending from the new-born infant to the superannuated
         dotard.                                  --De Quincey.
   [1913 Webster]

WordNet (r) 3.0 (2006):

nexus
    n 1: the means of connection between things linked in series
         [syn: link, nexus]
    2: a connected series or group