What does it take to slow a 120vac 60hz motor?

Is it a universal, induction, or what? Somebody may have an answer with a little more detail.

Don't know if it is universal, induction, or what. The motor is a hand held skill saw for cutting wood as carpanters use.

In this case you can probably use a solid state variable speed control. These look and perform like a dimmer switch and are designed for older ceiling fan motors. Most hardware stores should have one.