Definition from macmillandictionary.com
Is your computer turned on?
Turn on the outside tap, will you?
He’ll have to turn on all his charm to persuade her.
The hoses were turned on the demonstrators.
The trial turned on the medical evidence presented by the defence.
Dan suddenly turned on her and yelled at her to be quiet.
He’s very nice, but he just doesn’t turn me on.
That book really turned me on to astronomy.