The noun form of the adjective 'capacious' is capaciousness.
A related noun form is capacity.
I have a capacious amount of money.
Capacious means having a lot of room. The back seat of that car is quite capacious.
This capacious room will be perfect for our cotillion.
The word capacious means roomy or large, so a capacious waistline would be a big waistline.
This capacious cavern must be home to many of the bats we are looking for.
The boy carried a capacious(meaning : of large capacity) bag.
The living room was capacious enough to accommodate a concert grand piano as well as the other furniture
At first she yelled at her husband for building such a capacious garage, but all the extra space came in handy later when both of their children moved back home.I have a capacious head for knowledge, but unfortunately, most of that knowledge is trivial or useless information.
If you have a capacious lumbar spinal canal, it means that it is a wide one. Some people have wider ones than others.
capacious
spacious, large, generous, capacious, sizable
Spacious or roomy, capable of holding a large quantity.