Fascinated means held completely by interest in something. You cannot look away and you did not choose to be interested.
It takes by. The word is stronger than interested and quite different from entertained, since fascination can be uncomfortable, which is why people are fascinated by disasters. Snakes were once thought to fascinate their prey by staring, and that is where the word comes from, which explains the sense of being held rather than merely attracted. The noun is fascination and the adjective for the cause is fascinating.
1adjectivefascinatedCompletely absorbed and held by interest.
“The children were fascinated by the machinery.”