a city in southern California
"The traffic on Riverside was heavy during the afternoon rush hour."
A bank or side of a river.
"The children built their sandcastle on the riverside where the water gently lapped against the grass."
In plain English: A riverside is an area of land located right next to a river.
"We built our tent on the riverside to watch the sunset over the water."
At or near the side of a river.
"We built our campsite on the riverside to enjoy the cool breeze from the water."
In plain English: Riverside means something that is located right next to a river.
"The children played along the riverside path after school."
A place name applied to a locality, especially a city, that is situated beside a river.
"The new community center will be located in Riverside, the historic town nestled along the banks of the Colorado River."
The word riverside is a straightforward combination of the words river and side. It has been used since at least the mid-19th century to describe land located next to a flowing body of water.