1. verb To enable, connect, or start the function of something. In this usage, a noun or pronoun can be used between "turn" and "on." Would you turn on the water heater for me, please? I need to turn on the lights to see properly.

2. verb To suddenly attack, berate, or show hostility toward someone, especially after previously having been loyal or amiable. I know he seems friendly, but he'll turn on you in an instant if you disagree with him. The dog turned on its owner, biting him in the leg.

3. verb To shift or direct the focus of something onto someone or something. In this usage, a noun or pronoun can be used between "turn" and "on." Then the reporter turned the camera on me and started asking me about my involvement. Can you turn the lights on lead actor, please?

4. verb To depend on or center around someone or something. Our entire plan turns on them accepting this offer. The plot of the books turns on two brothers during the civil war.

5. verb To increase someone's sexual interest or excitement. In this usage, a noun or pronoun can be used between "turn" and "on." I know it's clichéd, but expensive cars and nice suits really turn me on. A: "All I need to do to turn on the ladies is just flex my guns." B: "I think I just threw up a little."

6. noun Something that increases someone's sexual interest or excitement. As a noun, the phrase is usually hyphenated. It's a big turn-on when a guy is a good listener.