In the US “sleet” is the term for a winter precipitation that occurs when snow falls through a layer of warm air and melts into water droplets, then re-freezes into ice pellets as it passes through colder air closer to the ground. In many other areas that were part of the British empire that precipitation is called “ice pellets” and “sleet” instead refers to a mix of snow and rain. In the US that’s called a “wintry mix.”
Where are you from? Based on your and OPs descriptions I’m guessing a Commonwealth country.
Being from the U.S. I’d have described it as frozen drops of rain.
Canada.
“Frozen drops of rain” makes sense too. I picture it as, “Imagine a raindrop hits your windshield, and instead of thunking like a raindrop, it’s kind of splats like a tiny tiny snowball.” That’s sleet.
In the U.S. sleet bounces off the windshield instead. I think we’d call Canadian sleet wet snow. OP said we’d call it “wintry mix” which maybe some of us would but I always thought “wintry mix” was when you were on the line between snow and rain and you just got a bit of everything; snow, sleet, slush, freezing rain, etc…