The engine suddenly 'roared (back) to life'. [=it made the loud sound of an engine and began running well]
The audience 'roared' with laughter. [=the audience laughed loudly for a long time]
The fans were 'roaring' [=yelling and cheering loudly] after their team scored.
(..) You know about that? Simba, everybody knows about that. Really? Oh, yes. Lucky Daddy was there to save you, eh? Oh, and just between us, you might want to work on that little roar of yours, hmm? Oh, okay... Hey, Uncle Scar? Will I like the surprise? Simba, it's to DIE for. Shut up. (..)1994 The Lion King
(..) I'm gonna be the mane event Like no king was before I'm brushing up on looking down I'm working on my ROAR!! Thus far, a rather uninspiring thing Oh, I just can't wait to be king! You've rather a long way to go, young master, if you think... No one saying do this No one saying be there (..)1994 The Lion King