Why did Muammar Qaddafi support terrorism before denouncing it in 2003?

Prior to 9-11-01 "terrorism" referred to the way a government treated its citizens. Amateur soldiers were called guerrillas. It was Dubya Bush who reversed the meaning. He did not provide a new definition, so now the word is an all-purpose insult for any activity that Americans happen to disapprove of. So if you want to talk about supporting or denouncing "terrorism", you need to explain what you are talking about.