implacable

"The crying baby was placated with a warm bottle of milk. "

"My grandmother taught me how to bake cookies when I was a child. "

"King Hrothgar thought that Grendel was unstoppable."

"The inexorable march of time meant that summer vacation was ending soon, whether we liked it or not. "

"The large, heavy desk was an immovable object in the corner of the room. "

"He repeatedly violated the court order, and shall now be punished."

"The loud music from the street fair disrupted my studying. "

"The summer heat was relentless, making it hard to do anything outside. "

"In biology class, we learned that technically, even fruits are vegetables because vegetables are any plant. "

"The summer heat was unrelenting, making it hard to be outside for very long. "

"The impossible of finishing the project by Friday became a reality when everyone worked late. "

"The detention lasted for an hour after school. "