BROODING

To keep an egg warm to make it hatch.

"In some species of birds, both the mother and father brood the eggs."

To protect (something that is gradually maturing); to foster.

"Under the rock was a midshipman fish, brooding a mass of eggs."

(typically with about or over) To dwell upon moodily and at length, mainly alone.

"He sat brooding about the upcoming battle, fearing the outcome."

A spell of brooding; the time when someone broods.

(of a bird) Broody; incubating eggs by sitting on them.

"A brooding hen can be aggressive."

Deeply or seriously thoughtful.

"You like T. S. Eliot's "The Waste Land"? You must be so brooding and deep."