working principle (noun)

1. The working principle behind the steam engine revolutionized transportation during the Industrial Revolution.

2. The working principle of a haunted house is to create an atmosphere of fear and anticipation.

3. In Greek mythology, the working principle of the Sirens was their bewitching songs that lured sailors to their doom.

4. The working principle of a pun is to play on words that have multiple meanings for comedic effect.