An extendible bridge for loading passengers onto large commercial airplanes; provides protected access to the plane from the gate WordNet 3.0 & Open English WordNet

A jet bridge is an enclosed, movable connector which most commonly extends from an airport terminal gate to an airplane, and in some instances from a port to a boat or ship, allowing passengers to board and disembark without heading outside and being exposed to harsh weather. Wikipedia

Enclosed movable bridge which extends from an airport terminal gate to an airplane Wikidata

An elevated corridor connecting an airport to a plane, usually enclosed and used for disembarking and embarking passengers and crew. Wiktionary