Boulder (noun)

A large, round rock, especially one that is too big to be lifted easily.

Origin:

The term "boulder" originated in the late 16th century and is derived from the middle english word "bouldre" meaning "a large rounded rock". it has been used to refer to a large, round rock since then.

Examples:

1. The boulder was a natural feature that had been there for thousands of years.
2. The boulder blocked the entrance to the cave, making it impossible to pass through.
3. The children played on the boulder and pretended it was a castle.
4. The boulder was used as a seat by the hikers while they rested.
5. The boulder was used as a landmark to guide travelers on their journey.