From Latin nexus (“connection, nexus; act of binding, tying or fastening together; something which binds, binding, bond, fastening, joint; legal obligation”), from nectō (“to attach, bind, connect, fasten, tie; to interweave; to relate; to unite; to bind by obligation, make liable, oblige; to compose, contrive, devise, produce”, supine stem nex-) + -tus (suffix forming verbal nouns).