Is it true that dinosaur actually mean terrible lizard?

Yep. That's what Richard Owens thought they were. As things turned out, they weren't that much like modern lizards after all; some people - mostly country folks - thought the fossilized bones looked like those of giant chickens, but their ideas were ridiculed by the scientists of the day. Well, guess what? Modern scientists have been able to analyze some of the DNA of the dinosaurs and they were more closely related to chickens than to lizards!

I don't think there are any moves underway to change the name to "Dinogalliformes" (terrible chickens), though.