the.com/docking clamp

means A mechanical device that physically locks two spacecraft (or spacecraft components) together to form a sealed, secure connection.

from A straightforward compound: 'dock,' borrowed from the waterfront world of ships pulling into berths to load and unload, extended in the 20th century to the sci-fi and then real-world image of vessels berthing in space; and 'clamp,' from Old English/Germanic roots meaning a device that grips or fastens tight. Put them together and you get exactly what it sounds like — the part that grips when one spacecraft comes in to dock with another.