Old word: flotilla.
New word: bascule.
If you’re wondering how to drop the latter casually into conversation, here are a few examples:
- The bascules of Tower Bridge were raised in salute.
- Tower Bridge is a bascule bridge.
- The bascule mechanism is driven by oil and electricity.
- A list of bascule bridges is available on wikipedia.
- I did not learn about bascules in scule.