Skilsaw was the name of the company that produced a successful hand held circular saw for wood. It differed from previous saws in that its blade was driven by a worm drive, giving an increase in torque over saws that have the blade directly connected to the armature of the motor.
This innovation was the invention of the Michel Electric Handsaw Company, the company changed its name shortly after going into production of the new high torque hand saw to Skilsaw.
Like many other successful inventions, such as the Hoover vacuum cleaner, the company name 'Skilsaw' became synonymous for all hand held circular saws, especially in the United States, but to a lesser extent in the UK where they are more often called circular saws.
The company Skilsaw was renamed Skil, presumably to accommodate its wider range of power tools. It subsequently became a subsidiary of Robert Bosch GmbH.