Definitions

1. noun

a person or animal that roars, especially a lion, or a person who produces a loud roaring sound

“The crowd of cheering fans was a deafening roarer in the stadium.”

2. noun

a device or mechanism that produces a loud roaring sound, such as a steam engine or a jet engine

“The old steam engine was a majestic roarer that powered the entire factory.”

3. verb

to produce a loud roaring sound, especially in anger or excitement

“The crowd roared in approval as the team scored the winning goal.”