The antonyms for the word "undock" would be "dock," "moor," "tie-up," or "berth." These verbs refer to the act of attaching or connecting a ship or boat to a platform, pier, or quay, usually for the purpose of loading or unloading cargo, passengers, or supplies. Docking is the opposite of undocking or disconnecting, which involves releasing or separating the vessel from its moorings or fastenings. The term can also be used to describe the process of securing or anchoring a vessel in a specific location, either temporarily or permanently. Docking can be performed manually, with ropes, lines, or chains, or using specialized machinery or equipment.