the highest or uppermost side of anything
"put your books on top of the desk"
"only the top side of the box was painted"
the highest or uppermost side or portion of something
"The cat climbed to the upside of the teeter-totter and balanced precariously on its edge."
In plain English: The upside is the good part of something that makes it worthwhile despite any bad parts.
"The upside is that we can go on vacation without spending any extra money."
Usage: Use "upside" to refer specifically to the top surface, such as when flipping an object over so its underside becomes visible. This term is often confused with "top," but it implies a position relative to being turned rather than just general elevation.
On the top of.
"The upside is that it allows us to see everything clearly from above."
The word upside comes from combining the words "up" and "side." It originally referred to the upper surface or top part of something.