annex: [14] The verb annex entered English about a century and a half before the noun. It came from French annexer, which was formed from the past participial stem of Latin annectere ‘tie together’ (a verb annect, borrowed directly from this, was in learned use in English from the 16th to the 18th centuries). Annectere itself was based on the verb nectere ‘tie’, from which English also gets nexus and connect. The noun was borrowed from French annexe, and in the sense ‘extra building’ retains its -e. => connect, nexus[annex etymology, annex origin, 英语词源]