A sudden attack of illness, especially a stroke or an epileptic fit.
Seizure can make people think of sudden and scary things happening to someone's body.
Examples:
He had a seizure and fell down.
During the seizure, he couldn't control his body.
The seizure made him shake a lot.
The seizure made him dance like crazy!
During the seizure, he looked like he was being controlled by a robot.
The seizure was so bad, he couldn't talk for a while.