bridgehead

bridge +‎ -head; A calque translation of the French tête de pont.

• IPA^(key): /ˈbɹɪdʒhɛd/

bridgehead (plural bridgeheads)

1. An area around the end of a bridge.
2. (military) A fortification around the end of a bridge.
3. (military) An area of ground on the enemy's side of a river or other obstacle, especially one that needs to be taken and defended in order to secure an advance.
4. (chemistry) Either of the two atoms in different parts of a molecule that are connected by a bridge of two or more other atoms

• (military): beachhead
• (chemistry): dibridgehead

• airhead
• beachhead
• railhead