PIE root ‘to bind, tie’.
Other derivatives include node, noose, and denouement from Latin nōdus ‘a knot’, nexus, annex, and connect, from Latin nectere (past participle nexus), ‘to tie, bind’, and nettle, from Old English netel(e).
[Pokorny *ned-1 : ned-, ‘to roll up; to attach, bind’, pp. 758–759.]