turn on

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turn on (third-person singular simple present turns on, present participle turning on, simple past and past participle turned on)

1. (transitive) To set a flow of fluid or gas running by rotating a tap or valve. [from 19th c.]

   Turn on the tap

2. (transitive) To power up, to put into operation, to start, to activate (an appliance, light, mechanism, functionality etc.).

   Please turn the lights on so I can see what I'm reading.

   Please turn on automatic updates.

   • 2006 February 17, Graham Linehan, The IT Crowd, season 1, episode 4:

     Hello, IT. Have you tried turning it off and turning it on again? Ok. Well, are you sure that it's plugged in?

   • 2011 December 14, Steven Morris, “Devon woman jailed for 168 days for killing kitten in microwave”, in The Guardian‎^[1]:

     Robins, of Torquay, had denied a single charge of causing unnecessary suffering to an animal. She claimed the microwave was accidentally turned on by one of the cats after the kitten got inside. But Knutton said the kitten was too small to even get onto the work surface.

3. (intransitive, of a device) To start operating; to power up, to become on. [from 19th c.]

   My computer won't turn on.

4. (transitive) To introduce (someone to something), and especially to fill them with enthusiasm (about it); to intoxicate, give pleasure to ( + to an object of interest or excitement). [from 20th c.]

   Attractive packaging can turn buyers on to a product.

   Attractive showroom models can turn buyers on.

   Hearing that song turned me on to jazz fusion.

5. (transitive) To sexually arouse. [from 20th c.]

   John's a maid fetishist. Maid outfits really turn him on.

   • 1986, Prince (lyrics and music), “Kiss”, in Parade, performed by Prince and the Revolution:

     You don't have to be beautiful to turn me on / I just need your body, baby, from dusk 'til dawn

   • 1987, “The Way You Make Me Feel”, in Bad, performed by Michael Jackson:

     You really turn me on / You knock me off of my feet / My lonely days are gone

   • 2010, “Teenage Dream”, performed by Katy Perry:

     You make me feel like I'm livin' a teenage dream / The way you turn me on, I can't sleep

6. (intransitive, slang) To take drugs.
   • 1971, Chuck Barnes, Revenge, Timely Books:

     "Well, they seem to always have dope up there, and I like to turn on, too."
     "You do?"
     "Sure. Cops is just people. I don't drink, so I gotta do something to get my kicks."

7. (transitive, slang) To cause to take up drugs, especially hallucinogens.
   • 1976, Robert H. Coombs, Lincoln J. Fry, Patricia G. Lewis, Socialization in drug abuse:

     In fact, many youngsters will not even turn on a close friend if they know he has never used drugs. And it is rare indeed for a youth to actively seek out people to turn on.

8. (transitive) To aim at.

   He turned the searchlight on the passing planes.

   Cornered by the authorities, the shooter turned the gun on himself.

10. (transitive) To rebel against; to suddenly attack. [from 19th c.]

    Suddenly all his friends turned on him.

    • 2011 December 14, Angelique Chrisafis, “Rachida Dati accuses French PM of sexism and elitism”, in Guardian:

      She was Nicolas Sarkozy's pin-up for diversity, the first Muslim woman with north African parents to hold a major French government post. But Rachida Dati has now turned on her own party elite with such ferocity that some have suggested she should be expelled from the president's ruling party.

    • 2020 June 14, Jitsiree Thongnoi, “Milk Tea Alliance: are young Thais turning on China over Hong Kong?”, in South China Morning Post‎^[2], retrieved 2020-06-16:

      Milk Tea Alliance: are young Thais turning on China over Hong Kong?

11. (ditransitive) To cause (someone) to rebel against or suddenly attack (someone else).
    • 1984 August 18, X-Con, “Women In Cages”, in Gay Community News, volume 12, number 6, page 7:

      We need to be thinking about what it means the way they are locking us up, and turning us on each other. We need to start fighting for our rights together.

12. (intransitive) To depend upon; to pivot around, to have as a central subject. [from 17th c.]

    The argument turned on the question of whether or not jobs would be lost.

• In senses 1-7 turn on is a phrasal verb with on functioning as an adverbial particle. If the sense is transitive and the object is a noun, the particle on may feature before or after the noun. If the object is a personal pronoun, then the particle on must come after it.
• In senses 8-11, turn on comprises the verb turn used intransitively and on functioning as a preposition before a noun or pronoun.

• turn against (sense 9)

• shut off (senses 1 to 5 inclusive)
• turn off (senses 1 to 5 inclusive + sense 10)

• keep on (senses 1 to 4 inclusive)
• leave on (senses 1 to 4 inclusive)

• Runton, untorn