A valley, especially a long, narrow, steep valley, cut in rock by a river.
"After hiking down the rugged trail, we marveled at how the Colorado River had carved such a deep canyon through the red sandstone over millions of years."
In plain English: A canyon is a very deep, narrow valley with steep sides that was carved out by flowing water over a long time.
"We hiked along the edge of the deep canyon to get a better view of the river below."
Usage: Use the word canyon to describe a deep, narrow valley with steep rock walls, often carved by flowing water. Do not use it to refer to any ordinary valley or open space.
An unincorporated community in Algoma district, in north-eastern Ontario, Canada.
"After driving through the dense forest of northern Ontario, we finally arrived at Canyon and checked into our small roadside motel."
The word canyon was borrowed into English from Spanish cañón, where it originally referred to a large gun barrel before coming to mean the deep valley we know today. It entered the language as a doublet of "cannon," sharing the same root but developing distinct meanings over time.