Ballast
Trestle is a word for railroad bridge.
A four letter word meaning the foundation of something is base.
What is a seven letter word with w as the sixth letter?
Fly.
Holiday is a seven letter word.
What is a seven letter word with o as the sixth letter
Luggage, is a seven letter word for bags.
Base.
base
In my dictionary the seven letter word after fan is fanatic.
A seven letter word for religious dissenter is heretic.
Duchess is a seven letter word.