Final answer:
In Washington Irving's story, the character Brom Van Brunt is widely known by his nickname BROM BONES, which reflects his physical strength and prowess in horseback riding.
Step-by-step explanation:
The nickname of Mr. Ambrose, widely recognized in the context of Washington Irving's story, is BROM BONES. This character, whose full name is Brom Van Brunt, is renowned for his physical strength and dominance in horseback riding, which has earned him his nickname. A fearless and boisterous figure, Brom Bones is also known for his love of mischief and good humor, despite an appearance of roughness. He is a central figure in the region's folklore and merriments, and his presence is often associated with energetic and likely disruptive activities.