On a hot day, you’ll be happy to have a fan that can oscillate, meaning it moves back and forth in a steady motion.
The verb oscillate can be traced back to the Latin word oscillum, meaning "swing," so it makes sense that oscillate is used to describe an object like a fan or a pendulum that swings from side to side. The word also can be used to describe a different kind of motion — the wavering of someone who is going back and forth between conflicting beliefs or actions. If you’ve ever had trouble making up your mind about something, you probably know what it feels like to oscillate — back and forth from one decision and to another and then back again. And again. And again.