lower lip
bottom lip

She bit her bottom lip in order to prevent herself from screaming.

She bit into her bottom lip so hard he expected to see blood.

The girl chewed on her bottom lip as she thought about it.

It rose up from outside the bottom lip of the window.

I touched my bottom lip again and found half a grin for him.

I put the feather to the very edge of my bottom lip.

She bit down on her bottom lip and tasted blood.

She bit down, none too gently, on his bottom lip.

She bit into her bottom lip in an effort to keep it still.

He had a tooth, that went straight through his bottom lip.