How do you define constant angular velocity?

Assuming you mean "Constant angular velocity", let's break it down.

Constant, meaning "something that does not or cannot change or vary".

Velocity is distance over time, or "speed". Angular velocity is the angular distance (such as "one rotation")

An example of velocity would be 60 Miles per Hour (MPH). That would be that in one hour, an object would travel 60 miles.

An example of angular velocity would be 45 Degrees per Hour.

For a real world example, Earth turns 1 full revolution every day. "1 revolution per day" is an angular velocity. Lets convert this to a different unit. There are 360 degrees in 1 revolution. Therefor, we can say that Earth has an angular velocity of 360 degrees per day." We can convert this unit again. There are 24 hours in one day. 360 divided by 24 = 15 degrees per hour, which is another example of angular velocity.

Simply put, angular velocity is the speed at which something is rotating.

In computers, angular velocity is commonly used to describe a mechanical hard disk drive. Hard drive speeds are measured in Rotations per Minute (RPM) and are commonly 4200, 5200 or 7200 RPM. The faster the speed of the hard drive, the faster it can read and write data.