v.1. To suddenly aim or focus something on someone or something: She turned the camera on the speaker. He turned the gun on himself.
2. To attack someone or something suddenly and violently with no apparent motive: The lion turned on the animal trainer.
3. To become disloyal toward someone that one was once loyal to: After years as an assistant, I turned on my boss and told the authorities about his tax evasion.
4. To depend on someone or something for success or failure: The campaign turns on attracting swing voters.
5. To start the operation, activity, or flow of something by or as if by turning a switch: Turn on the light bulb. Turn the generator on.
6. To begin instantly to display, employ, or exude some affectation: She turned on the charm. He turns a fake accent on when he doesn't want to be recognized.
7. Slang To take a mind-altering drug, especially for the first time: They turned on and passed out at the party.
8. Slang turn on to To cause to become interested, pleasurably excited, or stimulated by something: My aunt turned me on to jazz.
9. Slang turn on to To be interested, pleasurably excited, or stimulated by something: She turned on to surfing this summer.
10. Vulgar Slang To excite someone sexually.