Deeply or seriously thoughtful.
Broody; incubating eggs by sitting on them.
A spell of brooding; the time when someone broods.
Certain to act or be a specified way.
Physically secure and certain, non-failing, reliable.
Certain in one's knowledge or belief.
Yes, expressing noncommittal agreement or consent.
Yes; of course.
You're welcome; polite response to being thanked.
Without doubt, certainly.